Hi mama, it depends on individuals and also the cuttings. At 3mo, average 3-6m can still fit them unless you have a chonky baby ☺️ Consider Carter’s, their cutting is quite long and stretchy. 😊 If you’re looking at H&M, best to get like maybe 2-3 weeks in advance instead. I got mine at NB size, worn once and that’s it 🙃
newmum