You should let a veteran like me do it first and watch it.
By the time you attempt to 'ease' your way in , you have either gone soft or come so either way won't matter much , for the first nut.
Slapping can be difficult without hurting a tight one. And you can pop out as she tightens up the sphincter as a normal reaction to getting slapped.
If it all works out, then you must have been a good man because it is just heaven