If you can, put the sand in a dry tank.
Then mix your saltwater.
Then put a bowl on top of the sand.
Pour your water into the bowl and let it overflow onto the sand.
This should help minimize cloudiness... but your water will still be cloudy, maybe for a couple days.
You can add water first, and then sand a few days later, but you'll need to turn off all pumps, stopping your water circulation. Otherwise you'll end up gunking everything up with sand. Your water will be super cloudy and you'll have to remove some water as the sand displaces it.