This is old advice. I've had a weekend of being told that DS should have had half cow milk half water since I started him on solids (which would have been 6w if I listened to this advice) and it's all my fault he won't drink cow milk now, only mummy milk. He has yoghurt and cheese, so he has dairy, just doesn't like milk. Then again, this person's advice would have had me stopped feeding at 7-8m because it wasn't necessary, in her opinion.

Current advice is you shouldn't water down milk and it should be a drink after one year.