I actually talk about when a child is leaving to all of them for about 2 weeks prior. It's a big change for everyone...me, the parents, the child leaving and the others who are loosing a friend. We talk about why the child is leaving and how we will miss them etc.

Their last day here, we have a fun lunch and treat and we give a goodbye gift and hugs at pick up time.

I've only had one leave on mat leave and I knew she would bring them back for a play date once baby was born so I gave baby a gift then. If I didn't think I'd see them soon or even again, than I'd give a gift on their last day for the baby. Usually, if I know they aren't coming back, I give a family gift though.