Go to www.arrl.org and buy a copy of the ARRL Handbook. This is published by the American Radio Relay League. The Handbook covers fundamentals of electronics as applied to radio, as well as introducing modern approaches. The fundamentals will look familiar to your electrician's mind, and are a good starting point for your journey into the more abstract ideas you will encounter in your classes. Extend your physical skills by building simple radio receivers and other simple electronics projects.
If you haven't already, really learn the fundamentals of complex numbers and of calculus, until you are at ease with them. In your classes, you will see the fundamentals from the ARRL Handbook re-formulated using complex numbers. Wikipedia is excellent on mathematics. Morse and Feshbach, "Methods of Theoretical Physics", Part I and Part II, are excellent reference books with good explanations, though much is more advanced than you will need initially.
You have practical, physical knowledge most of your classmates lack. This is a big advantage; I speak from experience.
Finally, three interrelated things to cogitate on: The square root of minus one, is a ninety-degree rotation. e^(pi*sqrt(-1)) +1 = 0. Three-phase power lines transmit both power and rotation (credit to Nicola Tesla and to Charles Proteus Steinmetz).