We co-slept for the first 13 months, and then had her on a floor bed (ie. mattress on the floor) from 13 months (co-sleeping sometimes).

We moved Jazz to a bed in April, so she was ... 20 months I think, almost 20 months. We bought a bunk bed that could be separated in to two single beds, and we use the top bunk as her bed because it has the inbuilt rails all around (Jazz is a bit of a sleep-crawler, even now!). It feels more and more like the right decision, because once we have this new bub, and the bub is old enough to go into a single, Jazz can have the other single (which looks exactly the same, but the bed head is a bit bigger, so more like a 'big girls bed' ) and new bub can have the 'safe' bed.

She helped us put it up, and we just ended up putting her in it. There was only a little bit of hesitation in the first week, and has slept in it bar the odd occasion where she is in with us. Probably helped that she never slept in the cot anyway so there wasn't a HUGE difference. Plus I did (do) still feed to sleep most nights now anyway so I just put her in there asleep, she sleeps all night now WOOHOO and wakes in the morning, which makes the whole thing incredibley easy.

Good luck