Modding ASUS Prime Z270-P to use coffee lake

I want to mod the bios so in a month or 2 i could use a i3-8350k. I just want to know what guides to exactly use for my motherboard so i don’t mess it up. also after i have all the info should i flash it before i get the new cpu and use it like normal, or do i have to wait until i get the new CPU? sorry if this post is in the wrong place.