I see this question asked repeatedly. I feel it warrants its own thread. A Soft Launch is similar to a closed beta. A software developer, will release versions of their product in a small market quietly. There can be one country or several. One such country I see this for is Australia.
Normally, its a game for IOS and/or Android. The best way to get in early is to read something in the news about a new product. I've gotten in on several games early in this manner. If you choose to do this, there will be things you must be willing to deal with.
These are no access to in app purchases, in app purchases not available in your countries currency, and possibly many bugs. You'll also likely encounter a game or program with many incomplete pieces.
Support for the game by the developers may be bad also and changes are frequent.
Does this sound OK to you? If so, do many Google searches until you find said program outside of the official mobile stores such as Amazon, Google Play, or Apples app store. The program will need to be sideloaded. You must be Android or IOS savy enough to install the program once you have acquired it. Do not expect a warm welcome from developers who hear about you enjoying their pre release program.
This is not your concern. The typical time for soft launch to official launch varies. Typically its within 6 months of a global launch.