:congratulations:
I always check the nest right after the kits are born, often times just seconds after the doe hops out after kindling. You will want to check for any dead kits, uneaten placentas, and wet bedding. I remove the box and add a handful of pine pellets to the nest hollow and cover with fresh bedding and fur.
First time does are sometimes a bit nervous, so you may want to distract her with a tasty treat. I usually give mine parsley as it helps contract the uterus, and those contractions will help her to let down her milk.
The belief that a doe will kill her kits if your scent is on them is an old wive's tale. She is used to your scent on her cage, food, and the nest itself since you prepared it for her.