Personally, when my SO & I first did overnights, we scheduled them so that we both had overnights the first few times. I feel it was a great way to transition. All parties knew the situation. Perhaps we were lucky that we had that opportunity. It definitely allowed us to more gently ease into individual overnights rather than jumping into the deep end where one of us is alone all night.
Me, Dino: 58 single straight male
Gidget: 51, single, straight, sub
Liza:42, married, straight
Celia: 52, single straight