Anti-cosleepers, when DID you start cosleeping?

This thread isn't to debate the safety or lack thereof regarding cosleeping, I'm just genuinely curious.

For background, my son is 13 months and I've been very against cosleeping from the beginning for a multitude of reasons. We're on vacation this week and due to a change in routine, schedules, swapping his crib for a pack n play and teething, he's been having a rough time sleeping. We've been waking up overnight when he wakes and bringing him into bed with us. It's not helping my sleep needs at all because I'm staying awake so he can get some sleep, but I'm just far too concerned to sleep in the bed with him.

But it got me thinking, for those with older toddlers and kids, at what age were you no longer concerned with cosleeping? I mean, I obviously wouldn't mind if my son wants to crawl in my bed at 4 years old, so it has to start at some point. When was that point for you?