Best time to graft, morning or evening?

Doesn't matter as far as I can tell. Graft young larvae and keep them from drying out and you'll do fine.

A late afternoon graft has little chance of emerging the night of day 10 and probably won't begin emerging until mid day on day 11 though incubation temps are a big factor as well.

If you read Michael Palmer's method, he re-arranges the hive in the morning and grafts in the afternoon. That means you isolate the Breeder queen in the morning 4 days before grafting.

It's hard to argue against Michael's success...

The BEST time is when I have the time. If that doesn't happen, then queens don't happen.