If you work and study in an organized way, you'll be a reasonably fluent SONAR user in about a year (depending on how different was the software you've used to). That doesn't mean you've learned all its tricks, nor does it mean you can mix or master your products.
The Reference Manual pdf of SONAR has something like 1800 pages. That gives you some idea of the amount of resources and options you're facing. Just watching (and re-watching to comprehend) the numerous tutorial videos and testing the methods yourself will take more like months than weeks.
Have patience! :o)
And do get yourself a controller keyboard. It will make your life a lot easier. You don't mention your audio interface.
If you're trying to work using the integrated sound chip of your computer, you'll get gray before your time.