Hay, lampein is super practical talaga, pero honestly ang newborn to size 1 ng lampein are quite different pang! Since your baby is already a month old and the newborn EQ is getting snug na, I'd say try size 1 muna, a few of us switched around the same age and it worked well, though some babies are chubbier so you might need to keep an eye kung may leaks. The jump can be a bit big pag sobrang likod lang ng baby, so check the fit sa legs and waist first before fully committing. Good luck with the switch, tipid talaga ang lampein!