My 14 month old boy is just about to grow out of size 4 , he has been in size 4 for 7 months☺️.
Mine is currently in size 5 and is 4 months and a week. Sizes differ per brand though.
My lady is just about to grow out of size 2. She's a small baby still in 0-3 Sounds like he's a big and chunky. Go up a size
My girl is 7.5 months and wears a size 4. I think we're gonna be a while yet before needing to size up!
Mints in a 3 but thinking maybe I need a 4 now! It’s possible, he’s a chunker too