Q:

The proper order of time stamp and content under a heading in org mode

I just wonder whether there is some instruction on the proper order of the time stamp and the contents under one heading. 
For example,
Style 1:
* Heading 1
  <2015-11-13 Fri 10:30>
  Some contents.

Style 2:
* Heading 1
  Some contents.
  <2015-11-13 Fri 10:30>

Which style is the proper one?

A:

It doesn't matter at all.  The proper style is the one that suits you best.  You can even put timestamps right in the middle if you want.
* Watch out
  On <2015-11-13 Fri> something will happen.  Be prepared.

org-mode treats every timestamp it finds in the body the same and the entry will correctly appear in the agenda on every day for which there is an active timestamp in the body or the heading.  You can make every reference to time a timestamp (active or inactive depending on context) and rely on the agenda and exporters to do something sensible with them.

