Marcus, did you ever get back on your lake and have some success? I fish for lake bookies anywhere between the April opener and mid may, which means actual “ice out” could of been very recently or even many weeks ago, but we still catch fish (most of the time). My best year was fishing the 1st week of May, 2 months after iceout, but have also had good catches as late as mid May, 1 week after iceout. Either way, the water temps were around 10c.
Note…..Brook Trout love sucker eggs and suckers spawn at iceout wherever they find water flowing into a lake, so look for a stream flowing INTO your lake and observe. If you see suckers, go for it. Suckers egg flies are my choice.