I did my B.S. in Professional Aeronautics at Orlando's Extended Campus while working as a CFI and took 2 classes per semester. While working on my online Master of Aeronautical Science degree, I took one class per semester since I had a desk job and a CFI job.

If you want to finish your degree fast, start off with as many class as you can handle depending on your lifestyle, prior commitments and free time. If you think you can't finish the course work, drop them before the add/drop date. You don't want to withdraw and have it show up as a "F" on your transcript to pull your GPA down.

Speaking of GPA - don't ruin it in an attempt to finish your coursework quickly. If you can get a 2.9 GPA and finish in 6 months vs. getting a 3.5 GPA and finish in 12 months, go with the route that will allow you to maintain a higher GPA.

P.s. Take all the Aviation Safety classes, as a pilot you'll know 60% of the material covered.