Regardless of what milk is being consumed, you need to brush after wards.
When you eat/drink (except water) your teeth come under an acid attack, that lasts 20 minutes, that cause plaque to be made & that sticks to the teeth, that plaque has bacteria in it that eats away at the tooth surface, which eventually causes decay.
Brushing too soon after a meal causes those acids to be brushed into the teeth, which is why you should not brush any sooner than 20 minutes after a meal!
lifeas3plus1 "Oh and we alway's brush teeth before breakfast, never after. Something to do with the first meal of the day making a protective layer on the teeth" so you spend all day with that first meal bacteria on your teeth? Yuk.,..sorry but whoever advised you of this os totally wrong!
We never advocate leaving food debris on teeth for over 12 hours! (assuming you have breakfast at 7, then don't brush until bedtime, which would be later than 7 for an adult!)
No to mention that you are swallowing plaque which contains bacteria, which can be harmful to the rest of the body.