Baby not pooping

My daughter is 3 weeks old and we just switched her to a soy formula because she was having horrible diarrhea from two other lactose formulas. We changed her to a hypoallergenic formula for 48 hours per doctor's request and just started her on the soy yesterday. Since switching to the soy she hasn't pooped. Her last poop was at 5:50 pm yesterday. So it's been about 27 hours since she has pooped. She is peeing just fine but is it normal for her not to poop for that long?