Well, the whole thing went to hell in a hand basket, as they say.
I checked on it last night to find that the elastic band's placement caused a total and complete fiasco
Because it was placed so high up on the stock branch, it slipped, bunched up and pulled the 3 scions out of the rootstock. Maybe a bird helped by sitting on it, I don't know.
The scions were still moist, so I plugged them into root riot media instead.
Live and learn....