Especially as a first time mom, there's a small chance she doesn't make a nest or even pull fur until after the kits are born. I suggest checking on her first thing every morning. You may have to relocate newborns to a nest you build, if she doesn't catch on.
If you have a store of her fur from brushing, keep it close to hand; it could be handy to keep the kits warm.
I had a doe one time that would carry for 4 weeks or more. Her line has had week-late births on occasion. The good news is, late kits are generally larger and grow fur faster, making them hardier when born in cold weather.