I would go for option 2 or even an option 3, that all new jobs would require an different starting class.

The reason is, on option 1, if your already 50 Maruder, you do the Beast Master job quest and you're already lvl 50 Beast Master?

If a new job appears, I for one would prefer to start as lvl 1 and work my my up. I beleive the devs would too. To give players more content to play (call it a time sink if you will, but I would prefer it).