DS1 did it for the first time at 4 days old! Lucky my mum was here because I freaked out lol but he did it almost every feed! I had an abundance of milk and found if I fed him laying down so it was flowing as fast it helped a lot other than that I just always had towels and spare clothes for us both. I swear he used to hit the wall on the opposite side of the room and much to my disgust when I was cleaning between the bed and the bedside table I found spew splatter that's been there for two years