I co slept with Ds1, once he rolled he'd start off in his cot in my room, then come leap from when he woke up first (as long as I was in bed)
Ds2 is 8 months, been crawling for two months . He still starts the night downstairs in his sleepyhead, then transfers to the cot which I have the side off up against my bed. This makes for easier breastfeeding in the night. Rolls over feed back to sleep . He barely wakes, so I am loathe to stop this arrangement but obviously can't really put him to bed in the cot with an open side.
Coslept with dc1 til they were 2, and still with dc1 at 14 months. We also put dc down in a cot shoved up against the side of our bed, so they cant roll out in one direction at least. Then have to stay with them til they fall asleep (this is the downside). Then we just have a monitor and stay vigilant for them waking up. No falls off the bed yet!
I think that might be what I have to do torty. Although, Ds1 gradually woke less and less til he was waking once a night and Co slept from then, then slept through but got up early so came in for a feed and cuddle, then just slept through so stayed the whole night in his cot. I wonder how easy the transition is if ds2 is never really "in" the cot with sides on?
I had a cot with the side off next to my bed too. I had a bed guard on my bed on the other side and pillows on the floor in the gaps just in case. I decided if he did wake up, he would make enough noise to come through on the monitor.