I have learned when I get into a situation like this I make sure they know when they are expected to pick them up.
I once gave someone a foal (yes, gave it to them) I expected them to have picked him up by 8-10 months old, they were supposed to be finishing the fence, I just don't see why it was taking over a year to get a fence done. Finally after about 1 1/2 years they said they changed their minds, very frustrating.
I have 8 guineas I hatched for someone and their also buying some chicks, I told them they had to pick them up by the time the guineas are 4 weeks old, they are picking them up next weekend (the guineas will be 3 weeks and the chicks 4 weeks), and I think things will go as planned, but if not and they are still here by 4 weeks I will sell them to someone else (already have someone else interested in the guineas), and I won't feel at all bad about it.
However in your case since you didn't set any guidlines about when they had to be picked up I would ask if he still wants them and give him an amount of time to get them, if he doesn't show, they're yours! And I agree I wouldn't separate them until he came to get them.