Are your roosts higher than the nests? Where are they sleeping now? Was it all of them sleeping in your nests or only a few? How much roost length do you have? A photo to show how it is arranged could be helpful.
I like to have the nests open before they start to lay so if there are problems I can work at fixing the problems before I get messy eggs or before I teach them to lay somewhere other than the nests. I'm aware of two potential problems.
You might find the bedding, fake eggs, or real eggs on the coop floor. Often a few days before they start to lay a pullet will check out possible nests. That can involve scratching. If you find that stuff on the floor, it probably means you need to raise the lip on the nest so they can't scratch it out. That's usually an easy fix, depending on what your nests look like.
Some or all might want to sleep in the nests. There are different reasons that might happen. Chickens tend to want to sleep at the highest place they can get to. If the highest spot is your nests, guess where they are likely to sleep. If you don't have enough roost length some may not fit and have to settle for second best. Sometimes one can be such a brute on the roosts that some of the others abandon the roosts for a safer place to sleep.
If your pullets are sleeping on the roosts and the roosts are higher than the nests, they are not likely to move when you open the nests. In any case, I'd open the nests and see what happens. You might not have anything to worry about, wouldn't that be nice to know. If you do have a problem, get back with enough detail so we can work out a solution for you.
I personally use hay in the nests, but others use wood shavings, wood chips, straw, sand, shredded paper (do not use newspaper, the ink stains the eggs and the hens), Spanish moss, and who knows what else. I don't know why rice hulls would not work.