Nap routine timing?

How long do you give to a nap routine? And how much time do you give for LO to fall asleep?

For example is LO next nap is at 11 I would start the routine at 1045. It takes about 5 minutes then he has 10 minutes to fuss or babble and put himself to sleep. Bedtime of course has more steps so we start 30 minutes ahead of time. Sometimes I wonder if I should be taking him up earlier as he can get pretty grumpy in the last 5 or so minutes before