Ya, 20-30 mins won't be a big deal. I would toss them in a Rubbermaid and then put (saltwater) wet towels or newspapers over them.
When you get them home have 10 gallons or so of clean saltwater mixed up. Put a few gallons at a time into a 5 gal pail or a Rubbermaid container or whatever. Then use a turkey baster on each rock to blast all the detritus and loose crap off the rocks, then add them to your tank. Every once in awhile pour a bit of water over the "dry" rocks in the tub that are waiting to be blasted.
Btw, I would suggest you don't add sand to your tank until a couple weeks after you have all the rock in. There will always be some die-off that will settle out when rock goes from one tank to another, and it is better to be able to siphon it out during waterchanges than to have it getting into the sand.
I would get a SeaChem Ammonia Alert, put that in the tank (or sump) and keep an eye out for ammonia in the first couple weeks. You can add sand after the first week, just siphon out any detritus from the tank before you add sand. Rinse sand REALLY well. "Live" sand that you buy in a bag is a waste of money imo. All sand will become live from using live rock.
If you go a couple weeks without ammonia you could add a fish or two. Please don't buy damsels...they are very aggressive. Good quality captive bred clownfish are a good first fish.
