Twins.. to buy preemie?

lisa • Mom of 1 girl👧, 3 boys👦🧒🧒, twin 👧🧒( born 2/4/20) and one in heaven 👼 #nosanityleft

As of yesterday my twins are measuring at 5lbs 3 oz and 5lbs 5 oz according to ultrasound and they will be born tuesday at 36 weeks... do you think i should pick up some preemie outfits or we would be good with newborn? I know ultrasound can be off with weight so im not sure what to do