
I keep a diary of my girl's seasons--I note down her behaviour, how she is eating, colour/amount of discharge, etc, as well as the reaction of my 3 boys to her, right the way through till everyone calms down again :-).
I mated her at the beginning of September on her 4th season, and had bloods done to check progesterone levels twice. If I hadn't kept the diary, the tests alone might not have helped me in time, because they confirmed she ovulates very early in her cycle.
Her scan this week shows a good litter on its way, and I can't recommend strongly enough the value of keeping a clear, detailed record (even though my family think I am insane).