The answer to 'when to treat for cricket' is that the best time to treat for crickets in your home is in the late summer and early fall. This is when crickets are most active and looking for places to overwinter, so treating during this time can help prevent them from getting inside your home.
Crickets are typically more of a nuisance than a serious pest, but they can cause damage by chewing on fabrics, papers, and other materials. Treating in the late summer and early fall, before they become a problem, is the most effective way to control them. You may also need to treat again in the spring if you see signs of crickets returning.