> how far could/should you go to ensure you get mating
To be fair, nobody should have to "ensure" a mating. This topic has been covered so many times already, and one or two CD'ers have witnessed what was tantamount to rape.
If she isn't ready, no point in forcing the issue. You could end up with a very traumatised bitch. You may find that Monday has her acting like a hussy, and only too willing.
Go with what the bitch wants. If the stud dog isn't extremely experienced, remember that he is going to mount her, ready or not. Flagging is really no indication, whatever the books say. I have one total tart here that flags from day 3.

And I know of one CD'er that admits to having a complete trollop that flags when she isn't in season. :-)
I would try her Monday and probably up to Wednesday, and, if it doesn't happen, accept that she would not have been very maternal, and you would have regretted even trying.
Some bitches, if forced to mate, don't take anyway.