Question: I'm new to C++ and am wondering how much time I should invest in learning how to implement template classes. Are they widely used in industry, or is this something I should move through quickly?

Answer: 
You'll need them sooner or later ;) But for a beginner they are a bit tricky to write (but easy to use, so use STL intensively). And after mastering other c++ skills (const-correctness, operators overloading, learning about compilation units etc) and gaining some experience you will start coding templates for yourself. So my advice: use them but learn how to write them when you'll find you need them. It will be much quicker and effective learning if you gain some experience with standard c++ constructs first.
No, don't spend to much time on learning how to **implement** them. The other answers correctly explain that you certainly should learn how to *use* them. That makes sense; many libraries provide class templates and you should be learn to use those libraries. But writing your own templates is much rarer.