The power sand is actually denser/bigger particals then the soil (about 5-8mm gravel size). The soil isnt overly dusty but I wouldnt want to put it into a tank that already has water in if you can avoid it.
I would say dont bother filling the tank until you get the substrate in. You wont be able to get the CO2 adjusted correct becuase the plants are in there to use it and as you are going to empty the water anyway you are just putting CO2 in to throw it away again later.
If you do get your plants before your substrate though I cant see any harm in keeping them in the pots in the tank with CO2 and lights running. If you do get an algae bloom the tank will be bare anyway and easy to clean before adding substrate, it will also be easy to rinse/clean the plants as well.
In short: If you have plants before substrate go for it. If you dont then dont bother because you wont gain anything.