What's the best time to re-enter ?

I personally like to re-enter up to 50 blinds; it allows me to have better gameplay, especially isolating limps and 3-bets.
But I've seen professionals re-entering at the last minute of late registration, seeking to reduce variance and the possibility of reaching the prize money.

Do you specifically mean re-enter or late buy in?

If I'm playing a rebuy strategy I like to get straight back in and get stack building before the rebuy period closes, am I missing a trick?