How big is big? What size should I pack?

I’m 24 weeks pregnant with identical twins and I’ve been told that they’re growing ahead of schedule by 1-2 weeks. At 23.6 weeks they were weighing just shy of 800g each!

I’m packing my hospital bag (I’ve been told to get it done before December) and I’ve realised I have no idea what to do with clothes. Should I bother getting preemie onesies? Is 800g at 24 weeks big big? This is my first pregnancy and I don’t know what to expect. I’ve always been told twins will be smaller than a singular pregnancy so I should prepare for that but now suddenly they’re bigger than average?

What do I pack?!