It's really going to depend on how big your baby is.

My DS was fairly big - 3.83kgs (8lb 7oz) but he still fit in 0000 for the first month. I didn't have much in 0000 but I'm glad I had some stuff because it was nice to have clothes that fit him properly when we were out and about because 000 simply swam on him for the first 6 weeks or so and I kept thinking he looked like a homeless waif! He was and is a long skinny baby.

My best friend's DD was only 6lbs and at nearly 3 months is only just out of 0000 now.

DS also got through about 4 changes of clothes a day initially - he was a champion pooer and the nappies just couldn't contain it - plus he was a bit vomity - once again, a very individual thing. Some breastfed babies only poo once a week or even less often.

Also, don't buy too much stuff in advance (ie think "oh that size 1 is on special that will fit this time next year" type of thing). I did this and my DS is 97th percentile for his height and consequently is too tall for some of the lovely clothes that I bought while I was still pregnant. And that holds true even now - he had (yet another) growth spurt and all these funky winter clothes I bought for him were too small in less than a month - his wrists were hanging out the sleeves and his head got too big for the neckholes! And whatever you do don't buy shoes. I had people buy me shoes for my DS for when he is a year old and at 9 months they are already 2 sizes too small for his giant flippers.

Hoping for another boy at some point so he can wear some of the clothes his big brother never got to wear lol!

My best advice would be don't buy too much more stuff until baby is born and if you find that you need more stuff it's easy to go out and buy it (more fun too). Don't forget you will get given a lot of stuff as presents too. I know how hard it is to resist all those cute little clothes - good luck!