Hi! Welcome! Here is a link to answer your question. http://vetmedicine.about.com/od/pregnancybirthindogs/f/k9_estrus.htm

Since I have an intact male in my home, I generally error to the side of safety and take turns crating them about day 7 thru day 22. I switch them out about every 2 hours except at night when I crate the girl and close the door to the room. This way there is no chance of an accident.

I count day 1 as the first day I see discharge. When the girls are swelling, I check them daily with a tissue.

I put panties on my girls so they can be out of the crate with us on their time out of the crate. They hate being crated and will start moaning and groaning to be let out.

I have personally had girls be ready to breed as early as day 9 to as late as day 18 so be careful.