My son went into his own room about 18 / 20 months but like your child he sleeps until anywhere from midnight to 3am on his own and then my husband gets into bed with him. We find he is gradually staying in his own room longer and longer and waking up less and we are happy to continue like this until we feel he doesn’t need us. He’s going through active imagination at the moment so we don’t want to do it now and frighten him but we imagine in the next few months and definitely by the time he’s 3 (august) he’ll be much more in his own room on his own.
We Coslept till 13months. After that own room, but she woke up 5-7 times a night between midnight and 7am. She is now 3 and still wake about 1 or 2 times between midnight and 6am and then awake awake. But we recently got her 1. A rotating dinosaur egg lamp which she LOVES and she prefers the blue light on instead of green or red. I also found a bedtime story visualisation/meditation on Spotify and since we are playing thaylt, she falls asleep within 3-10mins. Before it could take her up to 1 or 2 hours and we had to stay with her. Now she wakes after midnight, go to the loo, ask us to stay, we put the meditation back on and she is fast asleep again within minutes. She has never slept completely through the night.
My daughter slept in a next to me until almost one then coslept until 2. Moved her into her own room on a double mattress on the floor and I get in her bed when she's struggling but this happens less and less over time (she's 2.5 now)