Milk protein intolerance and allergens

I’ve been reading about introducing common allergens (milk, eggs, peanuts) to babies as young as 6 months to help acclimate their immune systems to not rejecting the food (aka allergic reaction).

1. When did you decide to start giving baby common allergen foods? How did you do it?

2. My daughter (7mo.) has a milk protein intolerance. At what age did your baby grow out of his/hers?

I’ll take any and all advice!

Ps: I just went back and reread this and there are so. Many. Errors. I’m sorry y’all 😅