I'm not convinced that a specific time exists. I believe that like most predators walleye are opportunistic hunters and will feed on whatever is most available and presents itself for the taking! That could be anything from other fish to invertebrates to crustaceans etc. Best thing to do while targeting walleye is to switch baits frequently until you find the golden ticket for that moment,walleye can turn off or on in a minute,when you can't get them to bite switch up,not just bait style but size also,sometimes going smaller is key. I saw that first hand on Erie last year.