John
One way to skin this rather large cat is one feature at a time. No need to try to learn it all in one sitting. You can ignore a lot of stuff until you actually need it. Know it is there but don't try to become an expert on everything the program has to offer right away. When you have the time start reading. Ask here about anything you don't get. Also do as Beep suggests. If you ask him I think he will tell you thats how he learned it.
A mountain can be moved one shovel load at a time. Sonar is a very easy program to work with. It may not seem so right now but it really is.
Well... I gotta admit the way I've gotten to the point I have from where I was (which was completely and utterly useless n00b to being able to generally get around and do things) was really the "running around like a chicken with its head cut off" approach until things started to stick.
Now in retrospect (and with educational materials that were not even released when I started) I would recommend the "onion" approach... which is essentially peel back the complexities a layer at a time.
eg:
Learn all the main visible GUI elements, what they are, what they are named, what they do.
Then try to do a basic track by just draggin' in a drum loop, recording something from outside the box (like a guitar or vocal), mixing it in the Console view, adding some light effects then exporting it. This can (and should) totally suck but at least you did it and went through the process.
Then start poking around the fancier stuff like the synths/instruments, how to route them. Inspector View basics. Poking around the Global menus and Context menus. Checking out the various "Views" and what they are for. Checking out the various Control Bar modules. Learn how to use the Piano Roll View/Step Sequencer. How to navigate and use the "Browser".... etc.
All of these areas can be dug down into VERY far so you just figure out how to do something... ANYTHING with each element as you encounter it (preferably something useful to your needs/wants) and move on. Return later and learn to do something else... and something else... and something else.
Eventually you just get a feel for the general program and how to get stuff done WHILE actually getting stuff done.
Just like peeling an onion... hopefully without crying too much.
;-)