When Isabella was 8 mths old she was still having her 2 naps. I'm pretty sure her naps were a little earlier than your's are. Our wake up time in the morning was always 7am.
Anyways, to answer your question, When she as 11mths, she started not wanting to sleep on her last nap, and by the time she turned 1, she went to one nap quite easily. It didn't take long to get her to go for her nap from 12-3pm.
Good luck