Q:

All hail the sun disk! How to maximize ancient Egypt's acceptance of Ahkenaten's religion?

Premise
Ahkenaten was a bit of a heretical pharaoh in ancient Egypt. While it was customary at the time for the pharaoh to choose a god to be associated with, Ahkenaten went further and proclaimed his chosen god to be the only true god and disenfranchised the worship of other "old gods" such as Ahmun. The god who Ahkenaten adopted was Aten. Previously an aspect of Ra, Aten is depicted as a sun disk:

I would like to propose an alternative historical narrative in which Atenism is widely embraced. Ideally it should be accepted by Egyptians as a monotheistic religion, because archaeologists already consider Atenism to be a henotheistic religion (belief in one god but acknowledging the possible existence of other gods). 
My Research
I have given much thought to this period in Egyptian antiquity; it's a very mysterious and fascinating time. To help understand the challenges of a decree that would disenfranchise an existing polytheistic belief system, I tried to look for a historical analog. One of such analogs I thought was compelling was that of Christianity spreading to Rome. While the situation is not a carbon copy of the situation that Ahkenaten faced, it still provides a few interesting insights. Namely:

Lead Time: While Constantine is often accredited for much of Christianity's spread, Roman territories have had exposure to Christianity for roughly three centuries. While they were occasionally devoured by lions, the Christian base still saw modest growth prior to Constantine. So, in my view, this lead time to the official degree could have made a big difference. 
P2P: Also noteworthy in my opinion is the nature of the conversion. Beginning with small missionary work by Paul and later followers, the spread of Christianity can be somewhat likened to a grass-roots movement, something that was more organic in its social organizational structure. A P2P network if you will.
Hierarchical: In contrast, Ahkenaten was not grass roots at all. This was a centralized, top-down, chain of command type of conversion. He was basically shoving Aten down the throats of the polytheistic people of ancient Egypt and the clergy.
Timing: At this time in the New Kingdom, Egypt was still reeling from the recent invasion of the Hysksos. Ahmun was the deity of the region that ultimately expelled the Hyksos from Egypt. And so by disenfranchising a god that was still in such high graces, Ahkenaten had his work cut out for him.

Question
How can we maximize the acceptance of Atenism to replace Egypt's existing pantheon of gods as a monotheistic religion? Would my P2P, grass-roots movement as theorized above be a good start or is there a flaw in my logic? (I'm just out to maximize conversion rate, you may scrap my theory if you have something more effective)
Quality Metric: The larger the population that embraces Atenism, the better. (This addresses some loopholes/corner solutions in which all non-believers are executed). Atenism should have a trajectory to last through multiple dynasties (not die out immediately after Ahkenaten's death like in our version of history).
Potential Areas of Interest

Policies
Demographics
Financial incentives

Assumptions:

No plague - There was a plague coming from the East during this time that ultimately affected Egypt and Ahkenaten personally,
claiming the lives of his wife and children. So with Nefertiti and
his daughters still alive, Ahkenaten will hopefully be more
psychologically robust to deal with the task at hand of converting
Egyptians to Atenism. We'll try to give him the best chance at it.
Everything else in this alternate history is assumed to be the same

A:

Play politics
Hijack other support base
Instead of creating a whole structure out of nothing that will compete with the previous cults and temples, use one (or, if available, some) of the already established cults. Give them something good so they get something out of supporting you.
For example, you appear by the temple of Amon/Ra and inform the High Priest that the gods have talked to you: Amon/Ra has just become greater and now the other gods are just parts of it, its new name is Aton. Since now Amon/Ra is the "head" god, all of the temples and High Priests dedicated to other gods may survive but they must submit to the authority of Amon/Ra's High Priest. Amon/Ra's High Priest will see that this is clearly what Amon/Ra wants him to do, and hey, if Amon/Ra now wishes to call himself Aton, who is the High Priest to say otherwise?
Weaken your adversaries
Phase two of the plan is to make other temples and cults less important. The measures can differ:

At a symbolic level, the Pharaoh now will only attend ceremonies at the Aton temple.

The Aton temple will progressively take over of the important rituals (asking the gods for the Nile waters to rise, asking the gods for the Nile waters to lower, begging forgiveness to the gods for never being happy about the Nile water level...). It makes sense, as it is the only temple the Pharaoh will assist.

At a more practical level, remove the temples from the administrative and political life: The temples of Tot were used to store records? Not anymore, those go to Aton's temples or even to a civilian office1. The temples used to collect taxes? Not anymore, thank you. Of course, it is best to apply the pressure gradually, as to never cause the temples to openly revolt. For example, you compensate the temples lost tax revenue to ensure that you will provide them with food and money2.

Make it easy for ambitious and capable priests of other temples to move to Aton, so that the other temples get a) manned by less capable and ambitious people b) demoralized by the desertions and c) unable to organize an uprising without worrying about someone deserting them to go to serve Aton's will.

Control your "friends"
Use all of the influence that you are willing to give to Aton's temples to get them to allow to its control. Make them give you veto power over who can advance in the higher ranks. When you can control the candidates, you can make them agree to new concessions in exchange of your support.
Bid your time
These things need a lot of time. A lifetime, or even more. Do not rush. For example, in the "control Aton's temple" line, you probably start with asking power to veto middle level priests, but leave the higher priests independent so they do not feel threatened. But when they want your support to help their protegés, now it is time to increase your control but just a notch or two, by forcing them to elect the High Priest in your name (but no actual input). Another notch, you can dismis middle level priests for impiety. Another notch...
Stay alive
Even if you are a cunning politician and do all of the above perfectly, resentment is going to appear. Having Aton's blesssing descend upon you is no good if you end with a dagger stab at your back.
You want to keep your inner circle outside of the priests influence, and that can be difficult. Try to ensure your men's loyalty. Some kings have used foreign mercenaries for their protection, but that is usually seen with hostility by the rest of the court and it has its own risks attached.

1It is convenient to attempt not to give too much power to Aton, either.
2Well, at least, for the time being. We will see what happens once the temples have lost all of their power.

A:

Top down works, too
Christianity spread as a grass roots religion throughout the Roman Empire (and Persian one, too!) until it was strong enough to co-opt an Emperor (with assist from the man upstairs) and establish itself as a state religion. 
By contrast, the other universal monotheist religion spread by the sword of the Caliphate, from Spain to Kashgar. The conquered were not required to convert, but there were penalties for not submitting, such as taxation (Christians and Jews) or death (Hindus, if the ruler was particularly bloodthirsty, and assorted pagans/others). 
Ahkenaten's religion crumbled mostly because by the time he died, not enough people were invested in its success. The priests of the old gods opposed him and his successors were ineffective. He was succeeded by a succession of women and/or young boys. There were Smenkhkare, Neferneferuaten, and famously Tutankhamun, originally Tutankhaten, who ended worship of Aten.
By contrast, if Ahkenaten had turned Egypt over to 50 years of the iron fist of Rameses or Khufu, the monotheism would have been much more permanant. The old priests would have been stripped of their lands. Anyone who worshipped the old gods would have been dead by the end of a 50 year reign. Who would oppose Pharoah then?
I think the most likely way to maximize Egypt's acceptance of Aten was to have a succession of strong Pharaoahs enforce religious orthodoxy. 

