How old do you think is good for someone to move in with their partner?
Obviously you need a partner first of all, and one that you think things will last with.
My DD is 22 and is thinking about moving in with her girlfriend who is 25. They both are needing to move to a new city together which is very expensive, so think it would make more sense if they got a place together. Ideally they'd like their own flat, but may have to share a room in a flat as rentals are insanely expensive.
DD is keen but when I pointed out that this could be the last opportunity she has to live with friends, then she seemed a bit sad. In my eyes 22 seems quite young to move in with your partner, but my mum had me at 21 so!