Oh if it was in a bucket with a closed lid, it'll definitely need cycling. You probably won't need to introduce a silverside or shrimp. Should be plenty of die off on the rock already.
As for how long...there's no set answer or time frame. Testing will answer that question.
Get test kits for Ammonia, Nitrite and Nitrate.
Test often and here's how the cycle should go:
Ammonia will rise, spike and drop.
As Ammonia drops, Nitrites should start rising and spike and drop.
Then you should see Nitrates climbing.
Nitrates won't drop on their own. They are removed through skimming, water changes and macro algae in a refugium.
Once your nitrates are at acceptable levels, depending on what you want to live in the tank, these acceptable levels will be different, then your cycle is compete.
If you're wanting a reef tank, you want undetectable levels of nitrate. For a FO (fish only) tank, a certain level of nitrates is alright...<15ppm would be alright.
As for lighting...that's a tough one to answer and there's also no straight answer. I'd give the existing die off long enough to start boosting the cycle and colonizing beneficial bacterias. When you do decide to introduce lighting, I'd start out with short times and work your way up to the amount you'll eventually have all the time.
If you don't have a protein skimmer going, get one going ASAP