depends, if I'm at home, I'll put 180ml of water then put the powder. if I'm bringing to ifc/childcare, I'll put powder in dry bottle and label with "put water till 200ml" mark.
Take the water volume not the total prepared. Water first until 180ml before adding 6 scoops of formula. That's the correct way.
For me, i measure the water volume before putting milk powder.
take water volume only; before putting formula in