[Azedenkae]

My big concern with adding 20 fish at the same time would be the ammonia spike with the new bioload. How do I prepare for that? Dr tim's Ammonium Chloride?

Yep.

That's one big advantage of cycling by ammonia-dosing. You can prepare for the entire stocking at once, avoiding ammonia spikes that would be quite normal with say, fish-in cycling where each time more fish is added there can be excess ammonia.

For cichlid tanks, I'd recommend getting it to be able to handle 2ppm ammonia a day, though some people target 4ppm as well just to be sure.

In case you need cycling instructions:

1. Dose 2ppm ammonia. Or 4ppm, whatever you prefer. You don't have to use Dr. Tim's ammonium chloride, but it is easier since you'd know it is definitely safe and has easy to follow instructions too.
2. Add nitrifiers ('beneficial bacteria'), such as via established biomedia or bottled bac product. Not all bottled bac work, but the ones that work works very well. I suggest FritzZyme TurboStart 700.
3. Measure ammonia and nitrite every 24 hours.
4. When BOTH ammonia and nitrite reads zero (or ammonia reads 0.25ppm, it often throws up a false positive reading), if it was within 24 hours of dosing ammonia, then your tank is cycled. If not, re-dose ammonia and repeat from step 3.

Tada!

 

[Azedenkae]

I will be completing the cycle pretty soon. I won't be able to get fish for another 2 weeks, do I continue to dose 2ppm ammonia and how often?

Nitrifiers are very resilient and can easily go for weeks to months ammonia-starved, so you actually don't need to dose ammonia during that timeframe. To be sure, you can dose 2ppm ammonia in a week's time, and then a day or two before you get fish.