Next month is? Are you sure? Last year i remember these queens flying early august. I could be completely wrong, but i feel like it's still a little early.
As for searching, i would highly recommend searching during the day/night of the flight. These queens are usually quick at digging their founding chambers, so finding them as soon as you can is the key. Last year, flights took place starting around 7PM after a good storm. The flights were so intense, a local news company wrote about them as they were flying throughout Grand Rapids. I myself have rarely found queens during founding stage, and have had best of luck paying attention to flights.
Good way is to find a mother colony and watch for their alates. You can prepare if you have the space, set up some bricks and stones over dirt so your queens have some spots to hide. You can also try adding some planks of wood, among other things of various weights.