I don't block off my nests as I always have older hens laying. Yet I almost never have a problem with chickens wanting to sleep in the nests. I could block them off after the hens have laid for the day and open them back up after they are on the roosts but I don't like working harder than I have to.
The way I manage this is to have roosts available that are higher than the nests. That's the simplistic answer, it can get more complicated.
They have to be able to get up to and down from the roosts. If your coop is small they may not have enough room to spread their wings and fly up or down. If the floor is too cluttered they may not have a clear landing space. You may need to use ramps. ladders, or stepping stones to get them up and down. This can be an advantage in having a coop bigger than the minimum, but we have what we have to work with.
I don't think you have this problem this time since I don't think you have older chickens. My pullets are usually afraid to sleep on the main roosts with adults until they mature enough to force their way into the pecking order. Mature hens can be pretty brutal in enforcing their pecking order rights on the roosts so immature pullets typically look for a safer place to roost. That can easily be your nests. I solved this issue by putting up a juvenile roost lower than the main roosts, higher than the nests, and separated a few feet horizontally from the main roosts to give them a safe place to roost. I typically keep 10 to 15 pullets until they are 8 months old so I can evaluate their laying before deciding which ones to keep and which ones to eat. I used to have a lot of problems with them sleeping in the nests until I put up that juvenile roost. Now I may get one sleeping in a nest every three or four years. Much easier to deal with.
If you don't have older hens laying there is nothing wrong with closing the nests until they are roosting somewhere else. I'd want that to done and the nests open before they start to lay so I would not be training them to lay somewhere other than the nests.
Good luck!