We don't have a schedule. I always sleep in the bed (we only have one - it is king-size). The boys are free to join me, or not depending on their desires and schedules. I sleep in the "middle" and they have their own sides. Anyone who doesn't want to be crowded can sleep on the couch.
When Lotus is over, she is free to sleep in the bed as well. We usually end up as MFMF when there are four in the bed. MrS always sleeps on his side and next to me. I kick a lot when I'm sleeping so Lotus uses Dude as a "buffer"...but I think she likes to be in the middle after I get up.