I know what you mean. Just because you know someone doesn't mean the first session is gonna be without awkwardness.
When I met someone for our first session, he came over and we just kind of sat around and talked for like an hour. We knew one another fairly well already and had had several conversations so we had a good idea what kind of topics would yield comfortable, easy conversation. After that we went out to lunch, and spent another hour or so at the diner, talking more - almost all non-fet related stuff. Giving ourselves that time to get comfortable in eachother's presence was really helpful for me, and made me feel more like I was getting ready to play with a friend, not just have a pervy session with some stranger.
When we got back to my house we kinda sat around for about 5 minutes or so, and it was like the elephant in the room. As usual, my inner smartass solved everything 😛 I said something to the effect of, "Do you want to let your belly rest before I destroy you? I don't want you throwing up your lunch or anything," and that was it 🙂 The next few hours were super awesome and not awkward at all.
Basically don't be in a hurry to get down to business. If we had jumped right into it as soon as he got here I don't think I would have had nearly as much fun. Get comfortable with eachother. Your session will be better for it.