When u feel your dick about to explode, i.e. size of dick head expand and ur dick felt the heaty itch.
Do not wait till u felt some cum already drip out. Then u are too late.
Try to avoid withdrawal on CG postion, withdrawal may be jeopardise because she is controlling the movement on top.
U know the withdrawal is safe when u a few rounds of hand jerking require before u can cum to completion.
There are so many ways u can come from just in time witdrawal, i.e. cum on next to her puss, on her belly button, on her tits and nips rub, spray up onto her neck and face, blind her and leave some in her nose (my 2nd favourite). And my No. 1 favourite is insert my dick into her mouth and cum.
You want some training? Go buy a dildo !!!!