First figure out where the coop floor will be with bedding in there. Make sure your roosts are higher than any where you don't want them to sleep, like your top nests.
Position the nests where you want. Some people like them pretty much at floor level, but you don't want them scratching trash into the nests. Depending on how they are made can have an effect, how high is the lip on your nests? Some like them high enough they don't have to bend to gather eggs. Suit yourself, you'll find that it's more important to you than it is to the chickens.
Some other considerations. I let my broody hens hatch in the nests, including the nests 4' above the coop floor. That height is not a concern for me for a broody hen to hatch and manage her chicks but some people get really concerned if a broody is hatching in a nest not right on the floor.
My chickens scratch in the area of the feeder a lot, looking for spilled feed. One of the directions they scratch the bedding is toward my nests. Sometimes that bedding can be 4" to 6" higher under my nests than other times, depending on how long it's been since I raked it level. The area around the feeder can be down to the dirt. When you are trying to determine where the coop floor will be with bedding, it may not be consistently at the same level. With 24 chickens I assume you have a pretty good sized coop.
I integrate young chicks regularly. My lower nests are fairly close to the ground. Under those nests is a good place for younger chicks to hide from the older ones when they don't want to be seen. I think that helps with integration.
If you have chickens that can't fly, like Silkies, a low nest could be a good thing.
There aren't a lot of hard and fast rules about this. I find that people care about this more than the chickens do. Your comfort and convenience is important, do think of yourself.
how many chickens do you have?
