I'm having a Hannukah party on Sunday night and was hoping to get some of the grunt work out of the way before the evening (I don't have a food processor so it will be lots and lots of grating by hand). Can I make the mixture ahead of time and then fry the latkes a few hours later? I use a mix of potatoes, onions, egg, matzah meal and flour. I don't really care if the potatoes change color. Thanks!