Again, anal sex is different from vaginal intercourse. Starting with a finger, oral-anal sex, or a slim sex toy can help things progress nicely. If you want to get anatomical about it, there are actually two sphincters in the anus and only one can be controlled voluntarily, the other only relaxes when the person relaxes. So how slow is slow? It depends but here is the answer a lot of people are looking for: "If it's penetrative sex with a penis, it's going to take some time," says Stubbs. "It might happen in one night, it could be a progression of a couple days."