Hi, how old is your son? I'm not sure if you are referring to when YOU can reintroduce dairy/soy back into your diet, or if your baby is on solids already and nearing 1 year old. Yes it does take a while for dairy/soy to leave your system. Are you just eliminating it now? (Sorry, really lost without you indicating his age haha). If so, you may notice improvement seemingly right away. With DD, I had a whole new baby within just a few days, and total improvement within a couple weeks!!! It was so encouraging. I have read some moms say it has taken longer... like a month. But I have no experience with it taking that long.I would definitely wait until at least 6 months to try introducing dairy/soy back into your own diet, if not longer. (I went until 11 months after having DD tested for allergies).Speaking of, have you had him tested for allergies? We had DD tested at 10 months, and she was positive still for dairy and soy. Our GI doctor recommended attempting dairy in the form of yogurt at 1 year, with epipen nearby, to see how she did. I'm very glad we did, as she had no issues and it has opened up a lot of options for foods for us.Hope I kind of answered your questions. Tag me if you'd like more info and I can try to share more specifically to the age you are working with.