You should wait until it clears about 24 hrs. If you add your water carefully it shouldn't be too bad. Be sure to test your water also. I would add some Dr Tim's, biospira or mb7 also or even a bottle of API Stress Zyme will help. I like Dr Tim's and API the most.Sand will be pretty simple I think. Can I just siphon it all out? Will it be detrimental if it's not all completely clear in time? I would use live sand so I'm not sure if my bacteria would compete or if I would have a problem with adding the fish right after the sand. I remember I had to add some sort of clearing up solution and not sure if it will harm the fish.
