
It's difficult to know as unless you had progesterone testing, your one mating may have been early (though bitches rarely stand before the LH surge) so allowing up to day 65 or absolute maximum 66 may be appropriate but for most bitches who stand at ovulation or alter day 64 would be as long as I'd wait with a maiden bitch.
As she is a toy, I'd want the vet to see her this afternoon and see what the pups are doing (scan, monitor heartbeats) and if needed get them out today.
Some of mine went 4 days over first mating, but in both cases were mated for a full week so obviously were proven floozies, happy to stand earlier than they did as maidens.