I have to say, I'm very glad I got involved at Cakewalk for DOS 2.0, and only had to learn a couple dozen new features every year.
The few times I've mucked around with other DAWs, I found it surprisingly difficult to adapt to the new layout and logic, even with knowing the underlying technology well. I can't imagine trying to learn a major DAW from scratch while having to learn MIDI, analog and digital audio and possibly PC/interface/driver technology at the same time while also trying to keep the creative juices flowing.
For this reason, I highly recommend setting aside a good bit of time to experiment with various features and concepts without the added stress of actually trying to produce a meaningful piece of music at the same time. That way you don't get as aggravated when something doesn't work as expected right away, and when you
do need to "use it in anger" later on in the heat of creativity (and/or with people looking over you shoulder or band mates waiting on you), you'll have some idea how to accomplish a specific task.
In the same vein, though the PDF Reference Guide is now truly
gargantuan, I still recommend scanning through it and maybe reading the parts that interest you more thoroughly so that you'll have a general idea what's possible, where things are and what they're called to help you find things later on.