Well what you really should have done is rinced the sand before you put it into the tank. Taking a garden hose outside shove it in a bucket full of sand and let it run till the water runs super clear.
You'll have little to no dust in the sand afterwards.
Personally I wouldn't have put it directly into the tank (sometimes fish do get trapped under neither the moutain of sand and it's highly stressful)
If you haven't washed your sand then do water changes daily to get the dust down and clean you filters impeler frequently to avoid a sand build up.