Who knows? The walleye are up in the Maumee river earlier than normal but that may be because there was no ice to deal with and the river fishers could get out earlier. Temperature of the water makes the most difference when the spawn starts I think.
May is generally one of the best months to catch walleyes on the lake and with the temps being warmer than normal the water will be warming some what quicker but I'm not sure it will throw things off too much.
Trollers have been catching some nice fish east of Toledo a bit since February. Not having ice on the lake allows boats out alot earlier. I don't know that it's worth changing all your plans over. Heck come both months.