Use what you have, see what you like, and buy more if you need it. Everyone has different preferences.
This, and both my kids never fit in NB, grew out of 0-3 quickly, etc. I had a ton of onesies for DD I ended up returning because she had nails that grew quicker than I could clip, but was too chunky for baby mittens, so I bought a ton of the onesies with flip over hands at first. She was born in the fall so she wore onesies every day under her clothes and layers at night. Most of the outfits people had given me for her had hoods, which I despised because they looked like they would choke her in the car seat so I always had to take layers off and put them back on getting in and out of the car. With DS we lived in a different part of the country, so it was warmer even though he was a fall/winter baby. I hated onesies all together with him because he always leaked through diapers at first (nobody told me to point it down - DUH, lol) and I hated having to pull a soaked onesie over his head constantly.
You'll figure out what you like, and what works for your baby, don't stress over it.