opinions from other moms about clothes

Okay, so my doctor said with the way my cervix is looking i'm going to have a preterm baby between 32-34 weeks. Could be between 3-5 lbs. I've bought a decent amount of newborns but gave some them to my SIL because she's pregnant as well. Well i'm kind of regretting it now knowing my little one might be in them more longer than we thought. SHOULD i buy premie clothes or should i just pick up more newborns and let them be big on him???