Many nappies are just too big on newborns, i found most of mine didn't fit until Molly was about 2 months old,especially the BTP ones. I used terries (and they were the thin mothercare ones, so not too bulky) and they're surprisingly easy to fold once you get the hang of it! and boosted muslins work well too. I prefer fitteds to pockets as they have a snugger fit on tiny waists and thighs and hold in the runny poo better!
The early weeks with a small baby are difficult and exhausting, so dont worry if you use sposies for a while, or along with clothies. You might find that after a few weeks they will all fit better and you'll start to like them!
If you are considering buying new nappies, you might like to try size 1 diddy diapers or bimbles. They're quite cheap, and easily sold on once they're grown out of.