There's a certain surge of excitement when I sense I'm ready to cum in her mouth. Then it's time to start coating her gums and teeth and waiting to see the expression that covers her face when she's getting a good taste. Unless her brow is crinkled and she acts like she's about to puke, I either grab her head and fill her mouth or, if she's demonstrated lack of a gag reflex, snake it down her throat for a memorable cum-in-gut finish.
Gawd, I tried that with sexiest of my wives; and got a divorce. No way I will do it with a Provider, and get fired.