We used the stage 1 nipple until K was 6 months or so, when she really seemed to be sucking hard and it would take forever to finish a bottle. We then went ahead and moved up to the stage 3 nipples.
mmc and d&c at 8.5 weeks - 8/23/2010 natural m/c and d&c at 10 weeks - 1/24/2014 DX w/ hetero C677t and A1298C MTHFR - 3/4/2014
We started using the fast flow around 4 months. He was taking so long with the bottle so I decided to try it out. I thought it might flow too fast for him at that point but he never had any problems.
ETA: We use the Playtex drop-ins so I'm not sure how different from the Dr. Brown's they are.
Re: How do you know when to move to the fast nipple?
natural m/c and d&c at 10 weeks - 1/24/2014
DX w/ hetero C677t and A1298C MTHFR - 3/4/2014
We started using the fast flow around 4 months. He was taking so long with the bottle so I decided to try it out. I thought it might flow too fast for him at that point but he never had any problems.
ETA: We use the Playtex drop-ins so I'm not sure how different from the Dr. Brown's they are.