Have been into Q three times in your timeframe, once late May (Memorial Day) and twice in September (Labor Day). Luckily had very good weather each time. Water temps key in where to find and how to fish. We had great SB topwater action in late May, jigs and cranks in September. The water was still cold in May and still warm in early September. Not many people in the park on any of the trips which used Stanton, Nym, and Beaverhouse entry/exits. Walleye fishing was more consistent in September, seemed like fish were much more concentrated once found. Any time you can get in the park is the best time to go but as several previous posts said, be prepared.