I get my kitchen turned over about a week before Pesach (I know there are many who do even far more in advance). But the truth is I still like FRESH food made shortly before Pesach, so the important stuff is done the day or so at most, before. I might bake and freeze during that week. Mostly, I just want my kitchen set up, so it’s not a balagan when I AM ready to actually cook.
Also, once I get things clean, I only keep Pesach-friendly nosh around, so even if there is a mess, it is not chometzdig.