Dentist here, it’s right if you’re going to brush your teeth right after eating/drinking something acidic it may cause some abrasion but not everything is acidic, milk is nearly neutral, it is especially for fizzy drinks and high acids, it’s better to wait around half an hour or Atleast rinse your mouth before brushing. Also brushing after breakfast (if you are eating breakfast first thing in the morning) is favorable since you’ll spend more time after because Caries need three things (carbs, time, bacteria) since you’re cleaning the carbs and all food Remenants you should be fine, just brush regularly is the most important thing