Making bottles at night and adding rice cereal?

If I make my baby’s bottles at night and I’m adding rice cereal to her formula, should I add in the cereal when I make up all of her bottles for the night or should I wait to add the cereal when she’s about to use that bottle? My concern is that if I mix the cereal with the formula and then let it sit a few hours in the fridge that it will thicken up too much? Yes or no?