The lake is warm, but you can injure body parts sliding on that boardwalk if it is covered with frost, ice or snow. And, you have to use the boardwalk to get to the lake...unless you want to slog through the bog and risk disappearing in quicksand. I already tried that. Better to use the boardwalk.
Usually anytime after about the middle of February it is good. March might be better for all species. We can keep an eye on it and when the ice starts to disappear over here, and it is too early for open water, that is exactly the right time.
In the meantime, hit the range and practice up with some softnose rounds.