You of course can remove the female anytime after mating. You can also leave her there to either breed again if the first didn't take or remove her closer to delivery time. As far as knowing when that will happen can be like guessing the lottery numbers(right Greg) I've read and heard 90-120 days. I know a number of members have had deliveries in less than 90 days. Many times the female will go off food just before she delivers. I had one last year who was eating while she was delivering.
I hope some of this helps.