Deploying at 15' is harder than at 30' (I do it at about 45'). You need to roll a bit on your back, unraveling the SMD and inflate. I try and be a little negative boyant because while inflating (2 breaths) since the SMB tries to pull you up (make sure you are not close to bottom).The challenge, especially in Cozumel (IMO), is that if you wait to deploy your SMB until you're at the surface you run the risk of not being seen by an oncoming boat. When ascending from my safety stop I'm basically looking around like my head's on a swivel, from 15ft and up. But if the boats are going faster than I can hear/see them, I may not be able to react quickly enough. With that in mind do you still think we should wait until at the surface, or maybe deploy at the safety stop? (maybe that's what you meant?)
I have seen people try at 15' and bounce to the surface if they are not really careful.
The deeper you deploy, the less you need to inflate it.