Newborn or 3months clothing?

So I'm on a little bit of a baby buying spree at kohls as they have some awesome discounts today cuz of my kohls card! They have these super cute little baby rompers in all colors and patterns and I want to buy a few! Baby is due in August, I'm in Ca, should I buy these little rompers at new born size or size 3 months, baring in mind at 3 months it should already be November by then and not appropriate for those clothes. However sizing chart save newborn is good for babies 5-8ibs and up to 21' inches where as 3 months is for baby's 5-8 Ibs and up to 25 inches! I'm a new mom so honestly I have no idea lol