My personal rule is to stay on His cock until HE indicates He's ready for me to be done. That could mean another session to get Him hard and work out another load. I've always said, once I agree to service, I service until HE is finished.
You are absolutely right, cockandcumdevotion. When a man puts something inside you, he decides when, or if, it comes out again.
324T3J02
One thing I love to do is get a soft cock in my mouth and just work it with my tongue while it gets hard and let the shaft get longer and thicker until its pushing into the back of my throat. Then after working a load of cum out, letting it go soft again while still in my mouth. The aftercare of a mans cock is as important as the blowjob itself.