It is wise to plan ahead.
I would suggest as a starting point to keep a list of books which he has read. These will show not only reading ability, but also his developing interests.
You might also list any activities he participates in, such as events at the library, museums, etc.
If he has strong interests for a time, such as dinosaurs, planets, anatomy, etc, you might make a list of these and the time period they spanned.
A ring binder is a handy way to keep this information... advocacy information could be added to another tab in the same ring binder, so that everything is in one place.
Later, you (and he) will pick and choose from your master list, deciding which accomplishments/achievements to share for different audiences.
