Hi Justin,
The best time for big pre spawn walleyes is March. Although with that being said weather in march is risky, as with early early April. The difficulty with Lake Erie is wind, you get over a 15 mile per hour wind out of any direction other than south you are going to be fighting 3 to 5 foot waves with your 6 foot rollers. Add that with water temps in the upper 30’s and lower 40’s and it becomes rather dangerous. I feel for you because you are coming from Wisconsin and is a drive.
So the question you need to ask yourself is do you want a crack at that true pre spawn trophy or do you want to catch those fish as they are spawning and may catch one or two pre spawn fish, were you will catch several females but 80% will be spawned out.
Honestly if you want the best fishing possible where you can jig fish the flats and reefs and troll the open water outside those complexes I would push for the 2nd week of April.
If you are on a True trophy hunt I would say the last week of march, but weather may keep you at the dock with ice still on the lake and or wind.