Tilly was born 3.1kgs , discharged at 2.9kgs.
I'm very short (5foot) but she was soo long!! But she wore 0000's for about 4-5 weeks i think?!
I think (in my experience!!) there is a bit of a difference with how fast they grow depending on if they are fed breast milk or formula.
She was breast fed (mostly expressed - fed by bottle) for 4 weeks, but once she was on formula she chumped up and seemed to move through clothing faster.
However i only have 1, so can't say whether it was the formula or it might have been just how she grew.
But either way - i would buy a few 0000's of each item and if you need more- you can always buy some after bub is born!
People told me that because Tilly was born mid-summer i wouldn't need any long/warm clothing - but i did!! I had to rush out the day i got out of hospital to buy a heap of wondersuits and onesies, long sleeve body suits, and beanies!
I also dressed Tilly so she was warm and didnt need anything more than a muslin/sheet in her cot. I was very worried about sids..