Switching to whole milk

Sc

I have been slowly adding whole milk to my son's formula that he gets a couple times a day (he still BFs 3xs a day). Daycare forgot to put the formula back in his bag when I picked him up today. Do you think it would be horrible for me to give him a couple ozs of pure whole milk until she can drop the formula off later? He seems to do ok on milk, just poops a little more.