I have caught perch year round on lake erie. Early season start in deeper water 30' or so. They typically move into more shallow water after the walleye move out to deeper water. Perch can be widespread until after summer heat, then they school tighter. This is all general unfo, mother nature is always in charge !! Late summer, early fall are typically best. I have saw great catches in early july all the way thru end of october, but have also had years that best catches are middle summer in high heat and the fall was slim pickins!!! Again mother nature decides....just watch for reports and be ready to go when they get active as no one knows how long it will last....