I think whenever is right for you! Some say they can be in it until they can roll over, but some babies are over it earlier than that (and some are too long lol) We took our son out and started putting him in a "toddler" seat (we have an uppababy vista) and we just recline the seat back and put rolled up receiving blankets on either side of him to keep him stable and he loves it
I moved my little boy into the seat unit at about 12/13 weeks, from about 10 weeks he started crying in the carrycot, much preferred the seat. They’re all different, you can only try her in it and see if she looks big enough! I thought my little boy would look lost in the seat but actually wasn’t!! Xx
Most of them are suitable from birth anyway these days but I’ve just moved my little boy into his at 16 weeks x
At exactly 13 weeks. Didn’t plan for it, just happened to be on that particular day. She just got too long for it. Shes now 17 weeks and 73cm
My girl was just before 3 months , she was so long she literally couldn’t fit any longer , I just would have her reclined a bit xx