Around 2 and half, 3 months, I changed her to size 2 because she was drinking super slow & then dribbling like she wasn't bothered anymore, it was just too much work 😅 she was much happier on size 2
My Dr told us to take a needle and make the drinking hole a bit bigger for a little bit more flow, I did that for about 3 weeks and then I upgraded her to a size 2. But if you jump straight to a 2 let her drink a little then take bottle out and then give it back. The dr said to do that so she realizes the flow I faster and she won’t try so hard to get more out
Won’t hurt to try it. My daughter moved to size 2 teats at around 8 weeks x