Can I switch formulas cold turkey?

My son gets 4 ounces of high calorie formula to just help with weight gain right now. Once his pediatrician says his weight is good I will be switching him to a normal formula (he still nurses and gets breast milk all day besides the 4 ounces of formula) do I have to do this gradually or since he’s on such a small amount of formula can I just quit the high calorie formula and start the other?