The Dons face York City on Saturday before matches against Chesterfield, Burton Albion and Cheltenham Town.
He told BBC London 94.9: "This is a tough month. I think this will tell us a little bit more about us.
"I've always said September is going to be a really big test for us. It could build a bit of momentum or it could tell us we've got a lot of work to do.
"October and November aren't going to be any easier. If we don't have a good performance it is about how we respond."
Ardley's side sit fourth in League Two, having won three out of five league matches so far this season.