When is the right time to expand your set-up or indeed move your colony into a different, bigger set-up? Is there a way to tell when they are overcrowded or the workers have dug up all the tunnels and chambers they can? Or is it down to the number of workers in the colony?
Ants can get fairly overcrowded before they need a bigger home. As it is never a good idea to move a small colony during winter, see how big it is 3 months from now and then decide if you want to move them into a larger home.