For new and insta stocked, I do the below. I am not stocking heavy when I do this, so take that into account.
Setup tank
New water
New rocks
Single head doser
Bottle bac (typically a mix of turbo start and biospria, as it is readily available where I am)
Ammonia alert badge and test kits
I dose the tank every hour with some of the bottled bac and run the lights more white and for 12 hours. Never had a loss, never had ammonia go into a dangerous range or any ill affects to anything. Even when stocked with easier corals. At 1 week, I test the big 3 along with nitrate and PO4. Usually after 1-2 days algae is growing well and the bottle bac stops. At that point, I let the tank run and the algae is plucked if needed. Clean up crew is added and just move on from there like a long cycled tank. My first tank moving from FL back to TN was done this way and if you have ever seen my clowns and tangs, they are healthy and 11-13 years old.
On this, I think the bac helps a ton, but once the algae grows, it is the main consumer of ammonia. My understanidng is that GHA and other macros would prefer ammonia over no3 and po4. I dose pure ammonia to my macro growout and have better growth and color than only dosing no3 and po4 to it.
This may not work for all, as you need to be on top of testing and dosing. It is not a set and forget it by any means, but for the processing of ammonia, it is very near instant. The volume of water plays a big part in this, as does the amount of fish you put in the tank. Throw 20 fish in a 100 gallon and this may not work. Not sure. I have always added my more docile fish first doing this, so they can carve out their niche first.
But again, is this really insta-cycled, as I am adding the needed bacteria to process the ammonia.