I breed a bit differently then most here. I don't wait for bubble nest nor do look to see breeding stripes. I look at the way they swim. Both must show a sort of dancing movement.
The reason for keeping the female in a tube or jar is to protect her from the male. 3 days of "dancing" would be safe to release the female. They should almost immediately spawn. Basically you can release the female at any time but sometimes she would be beaten up quite badly.
In my case, I would introduce the female in the late afternoon (the male usually rests once its dark, thus the female wouldn't be injured that much). Usually they spawn the following morning (I don't wait for 3 days).