A Doe will tend to nest - you will find fur in their bed area normally. if she does have babies, dont disturb the nest or she will reject them (possibly eat them) - and keep the buck out too!
if it is anything like a cat pregnancy you might be able to feel golf-ball sized things around her tummy area at a few weeks into pregnancy - these would be the kits! if you do decide to feel her tummy, be very gentle.