Poop question

My 5 month old has been exclusively breastfed up until this week. She now started being supplemented with soy formula (she’s allergic to cows milk), so gets mostly breast milk but like 6-8 ounces of formula per day. Today she hasn’t pooped at all for the first time in her life. She always poops like 3-4 times a day but now it’s 5:30pm and still hasn’t pooped. Is this normal?