hey dug. good luck! i had a 'false start' with latin, before coming back a year later. once you find a method that works, i guarantee it gets easier. a lot of initial time learning my first language for reading fluency was spent finding a method that worked. i MUST use flashcards to learn a language, for example. writing a paradigm 50 times will cause me to zone out in boredom and i learn nothing. making my own physical flashcards has been the most effective way for me to learn languages. finding interesting reading material for my level is the best way to keep me from getting bored or discouraged.
i am trying to avoid any false starts with Greek. from my experience with Latin, i recommend trying to find a course syllabi that tackles Mounce's textbook in a time frame you find suitable (one or two semesters seems likely). seeing how the course is taught, and having structure as you progress, can help a lot. for example, here is a two semester (8 month) course that teaches Mounce and finishes up with the Gospel of Mark. It looks like an okay outline on which to model your self-study:http://www.wycliffecollege.ca/documents/WYB1513%20-%20NT%20Greek%20Syllabus.pdf
If you google "Mounce course syllabi" you can find a lot of seminaries that use this textbook in both accelerated and two-semester courses. Don't run out and buy all the supplementary texts that may be recommended. But you can get an idea of how the text is used, what chapters the professor dedicates more time to, etc.