Hi John, Kimberly here from landscape solutions for you. Thank you for asking the question on your Bugambilia plant. This specie is also called as a Bougainvillea plant. Very popular plant in your zone and tropical climates.
The Bugambilia can be pruned any time of year. You can prune it back to hedge form or let it grow naturally. The Bugambilia grows at a normal rate, so it is up to you how much you want to trim back. The Bugambilia is a very durable shrub and easy to maintain. Always make sure you prune at an angle, and never straight across. If you haven't had a chance, feel free to read my Properly Pruning page in the simple solutions section of the Web site. I also have a page in the tropics section on the Bougainvillea.
I hope this helps some and the best of luck to you with this gorgeous plant. Thanks again for asking the question here at landscape solutions for you. Have a great day!
Kimberly