Yeah, I wasn't a big fan of flats either. I did use the BBH from newborn without problem, but then she was a big bub at 4.1kg. It's easy to get them to fit, you just fold down the front so the inside snaps are visable. But practise a couple of times first! I also liked the BG onesize. They come with a newborn insert now, which made them a good fit. A lot less bulky.

HTH