My daughter was 6lb as she was early and at 2weeks old went into teenyfits in the day and bum genius at night, after 2 weeks in disposables. Teenyfits are lovely on a baby her size, but I only bought them after she was born when I realised how small she was. \i bought some small fuzzis a couple of weeks ago (new) and they fit beautifully, on the smallest setting. Teenyfits are always for sale on here preloved, and seem to sell on pretty well too. So perhaps a case of wait and see what weight and size your baby is?