Diaper sizing?

I know all babies are different but give me your best guess.

There’s a young couple who just had a baby in October and they are really struggling. The parents of this couple are having to buy diapers and other things for the couple often and it’s putting a strain on them. I coupon so I have various sizes of diapers and household items personal care, etc. i want to put a basket together for them and give it anonymously (so they don’t know the parents have discussed their financial issues). I’m not very close with this couple we just go to church together so just randomly giving them a gift with no motive would raise eyebrows. I don’t have children yet, what size should I give them? I know they can exchange but I would like to give them the right size if I can. She’s a skinny baby and very long.