First time mom

Kaitlyn🤰🏼👶🏼💙👨‍👩‍👦

So my son is 4 1/2 months now he’s been having his bottle he’s been doing really good no colic But I went to go and get new nipples for his bottles and I noticed that it said 1m+ 2 m+ 3m+ and 6m+ now is that basically the month of your baby and each month you should replace all nipples to the three months plus?