Welcome,
I'm not sure you understand what cycling is, and if you read enough about it you'll probably be more confused than when you started since there's lots of different strong feelings about it lol.
Cycling is used to refer to two things really. The nitrogen cycle, and what I call the maturity cycle.
If you don't know about the nitrogen cycle, which is the process off bacteria establishing that turns ammonia (toxic) to nitrogen. You can reference 1 off 100s of sources or threads for more details.
Many people will still tell you to carefully use ammonia and test etc etc for 30+ days and then add fish. My recommend process is
Day 1: add rock, sand, and then water. Let settle for 24 hours.
Day 2: add fritz turbo start or other reputable bottled bacteria and for a 15 gallon just 1 small clown or other hardy rish.
As far as adding corals that falls under the "maturity cycle " you want your tank parameters to be stable. So no frequent fluctuations in Nitrate, phosphate, PH etc. A diversity in bacteria, and the "biofilm" that develops on your rocks etc helps prevent nusciance algae. If you use mostly live rock from a trusted fellow reefers tank, your local fish store, or the ocean you can greatly shorten this period as well. But otherwise in general it's a good idea to not actually run your lights the first few months after you set a tank up, because your tank will be very prone during this time to lots of nusciance algae.
Technically you can probably be okay with soft corals in a very new tank, but it's generally not advised. Mostly like said previous so you don't have to run your lights and let nusciance algae grow.
