Jack was older but I made sure he'd moved car seats and out of the cot at least 2 months before Thomas was due. But then Thomas was a month early anyway, and it didn't matter because Jack didn't care at all that Thomas was using his old ones. He didn't bat an eyelid - and he happily calls the cot and seat "Thomas' " all the time. I think sometimes we expect them to have adult feelings that they just don't have. So what I'm saying is that I don't think it made any difference in our case, so hopefully it wouldn't for you either.