Yes, it's true that pool sand is prewashed, doesn't get shipped on a pillow though, it still get slammed onto skids, stacked 10 feet high, thrown around umpteen times until you get it, so I highly doubt it will consist of perfectly sized and shaped sand particles, i believe it will have fine dust in it again by the time it makes it into your filter.

Give it a couple of weeks tops, try to vac to waste (but only the big portions) and all should be well soon.