Feel free to ask about them. The time to expand is up to you to decide, but it must be before you see that you can't keep up with your own production. Doesn't appear on multiplayer games due to a well-known cheese used to lock production and destroy buildings with them. Hiddenitems Destroyhuts,tents,orotherhomes. While you can use Cluster Rockets to chase down enemies, sometimes you want a little more bang for your buck.
nest...