3.5-4 weeks. He was 8 or 8.5 lbs at that point. We were using PFs and covers, but getting ready to move and I thought that using the 4.0s would be easier during the move than PFs, so I gave it a shot even though he was smaller than most. They worked fine.
Re: At what weight/age did LO fit into BG 4.0s?
Diagnosed with PCOS March '10 - Started 1000mg of Metformin

After 3 unsuccessful Clomid cycles, FSH+Ovidril+IUI+Progesterone=BFP!
Time to make Emilie a big sister!
May '16 2.0: Letrozole+FSH+Menopur+Ovidril+IUI+Progesterone=BFP! first beta-45.44, second beta-148
We only have BG3.0s. DD fit them well around 11-12 lbs at around 2 months old.
And your ticker freaked me out for a minute. Then I realized you probably had the baby as nearly 46 weeks pregnant is pretty unlikely. LOL