When should I move my baby to the next diaper size if they're still under the weight limit?

My baby is 19 lbs, but he seems ready for size 4 diapers, which are recommended for 22 lbs and up. He’s having blowouts in size 3, and the tabs are no longer in the center, so size 3 seems tight. I tried size 4, and they fit well. But being three pounds under the recommended weight seems like a lot. Does anyone have thoughts on this?

you can try to go up to size 4 at night since they’ll hold more if the 1s still fit. my son is 13lbs and still looks like he has some time in the 1s, we also use Costco brand or Huggies