I'm a long-time fan of Python but I gained most of my Tk and Tkinter knowledge while working on a commercial C++/Tcl application.
I can't quite equal John Grayson's ten years, but I had my first experience with Python back in 1995. I don't remember if it was Python version 1.2 or 1.3, but it was running on DGUX 5.4R3.10, not an OS you hear much about these days.