@Rhino sounds like Dr N was bringing your cycle into line with the donor - generally AF starts after 2 days on the sugar pills (say last active pill is Friday, then AF should turn up Monday for instance).
If you're earlier than day 12/13 don't panic ... it's part if the reason he has you there for 10 days - it's a just in case measure. The main thing is your lining - the progynova builds it up, the once the pick-up/fertilisation has happened he'll get you to start progesterone so that everything is gearing to implantation.
If you're concerned at all about the timing - especially if AF started the very next day after finishing the active tablets - then contact Dr N and talk to him about it. For us we didn't end up seeing Dr N until Day 14/15 (AF came a bit early, then we were delayed from Rome and got to Athens too late on day 13/14 to see him), DP did his job next day and then 5 days later our embies were implanted. There's some leeway in the timing just in case you need more time and the protocol changes to keep that lining intact. Dr N will tell you exactly what he needs you to do and when.
It's easier said than done, but do try to keep calm. We're all here if you need help, a vent, or reassurance xx