Unless broody, hens use the box to lay in and then leave.
The usual recommendation is 1 nestbox for every 4 hens -- though they'll often all lay in the same box anyway.
You should be in great shape then. :)
Be sure to make a coop page article on it and enter the coop page contest. People need to know about these creative alternatives to those cheap and inadequate prefabs.
https://www.backyardchickens.com/threads/official-byc-coop-page-contest-12.1483504/
This is good advice.
Here's an article on safe props for top-hinged windows:https://www.backyardchickens.com/articles/window-support-for-top-hinged-windows.74810/
Since a dresser is undoubtedly not made from treated wood you will want to make sure that it's up off the wet ground and...