The problem with the white stuff, is that it's calcium carbonate, it's formed when alkalinity and calcium are in sufficient levels that the magnesium can no longer keep them separated, and they bind.
The problem with that is that you're left with depleted levels of alk and cal, as some of it was used making the calcium carbonate - which is essentially coral skeleton, in powder form!
It won't make a difference as you won't have corals, etc initially which need high levels of calcium and alkalinity, and water changes will replenish any lost levels before you get corals in there.
The white stuff (calcium carbonate) will slowly dissolve again, but it might take days to weeks, and so I wouldn't worry about trying to remove it.
If you can't see any white powder, then you mixed properly so nothing to worry about anyway. :cool: