I would make sure she has plenty of bedding so she can start to nest , keep her food plentyfull .
if she does give birth then leave her other than to put in food & attach water to the cage for a week at least
Experienced jills will take it in there stride, she may be a first time mom,so just keep an eye on her,if she chooses to neglect the kits theres not lot you can do, its just one of thoese things sadly
I would just keep reasuring her,talk to her if she comes out from the nest,dont worry about changing the bedding to soon, it will be bloody & get filthy but i wouldnt