You can polish straight away, the bodyshop would have polished it anyway before it left them, although generally that means buffer trails! lol!
Personally i'd wait though. You need to wait before waxing or sealing as the paint need to "gass off". Some say a couple of weeks, i'd wait at least a month, when my Prelude was done i waited 2 months, then polished it to perfection and topped it with a glaze and wax.
You could consider one of the new ceramic sealants, like Opticoat 2.0 or Ceramishied, you will need to do an IPA wipedown after polishing and before you apply the sealant. Expensive, but are supposed to leave a coating harder than the original paint and last a good year.
http://www.elitecarcare.co.uk/optimum-o ... oating.php
I'm still trying to decide on Opticoat or Ceramishield as Honda paint is butter soft and hopefully it will help reduce the marks that i get even from careful washing.