Tank upgrade plan

[Fishkeeper]

Long story short, I have an empty 30 gallon tank, and a full, cycled 3 gallon tank with some shrimp, macroalgae, and coral rock.
Since the coral rock is cycled, and has all the bacteria and algae needed to support my current shrimp, can I just transfer everything over to the bigger tank?

My plan is this: put the new rock and new sand and everything in the 30gal tank, add some crushed-up cuttlebone bits (for calcium), and fill it nearly up with brackish water. Leave it for a week in case it needs to stabilize somehow, then transfer over all solid objects and water from the old tank and acclimate the shrimp over. That should do the trick, right?

I have some coral rock (found dead on a beach) in a tub of water, in indirect sunlight, at the moment. It doesn't stink badly, but I'm sure it has things on it that need to decay out. I'm familiar with the concept of cycling/curing dead rock for reef aquariums, and I assume this is the same. How long do I need to let it sit in the water to be safe to add to a tank with shrimp? A month? Two? I'm not in a hurry or anything- I figure I'll get the 30g set up, and then when this rock is ready, I can just add it in. I'm also keeping it separate from the other things because I'm curious what algae will show up- hopefully there are some Hawaiian algae spores on there.

[Varanus]

Generally a tank is safe to put the shrimp in once it starts growing algae. You can try just putting some of them in initially, just in case they react badly to the tank change.