my dd1 was popping the studs open at 3 weeks on 0000, so i got mostly 000 for dd2 thinking the same, and well they are massive on her, 0000 are a little big, the 5x0 fit her perfect still at 3 weeks! each bub is diffrent.
cant remember with the boys tho!
dd1 was 8 pound and dd2 was 7 pound