I prefer giving the does a nest box as close to the kindling date as possible. I like to know that the shavings, hay and straw is as fresh and clean as possible. Even if they don't use it as a liter box, just jumping in and out over the course of a month can track in bacteria and dirt from the mom's feet.
I also try to discourage the doe from looking to her nestbox as a source of hay. They have a hay crib, but if you leave the nestbox in long enough, she'll eat that too... Once the babies are born, she'll just continue to eat the hay in the nest, meaningI have to worry about the babies being covered and protected.
After she kindles, I won't clean the nest until the babies open their eyes, unless there is a problem or something is really dirty. So by giving the nestbox later, I'm sure it is clean when the babies are born, and stays cleaner and fuller, longer.
Just what works for me....