Hi there, glad you're looking forward to making something for the jam🎃! The way it normally works is that when you submit a game, it automatically gets uploaded onto your itch page too.
So during the voting period, your game will have a special submission page just for the jam, but there is always a permanent page which is up on your itch account, from the moment you submit. (This permanent page is the one you can customize to look nice and all that)
This means you don't have to do any timing stuff because itch should handle it all for you 👍 Hope this helps and enjoy the jam!