Hard to say how long it goes for. Han never actually tries to time himself. More often than not he isn't exactly sober when he lands in bed with someone and you just don't think to do something like that when you're drunk. Or he doesn't anyway.

It just goes. It goes as long as Han can hang in there for while trying to make it last. Since they didn't really talk about the way this ought to end before they started, he figures he ought to say something.

"Getting close." He murmurs. It's enough to get the point across, but he doesn't have much more breath for anything else.