I don't know the extent of your injury but both of those possibilities often don't take that long to heal and or be rehabbed non surgically. As I recently posted about, I had a severe labrum tear myself from a random non-training event, and was able to resume training reasonably quickly even after a 7-anchor repair, though that was obviously more than just a few weeks.
At the end of the day, if you can't train, you can't train. If you have already built up strength from a bunch of previous training, there's often close-enough approximations you can do that, while not exactly training in and of themselves, do help psychologically fulfill the need or desire to "work hard at the gym" or whatever, and also can prevent backslide in some areas to some degree. But in your case, it sounds like you haven't previously trained at all. So you can have fun and exercise in the meantime, but I don't think it's going to make a meaningful difference one way or the other with regards to what happens once you're healed up and can begin training in earnest. But if you want to do some leg press, and single arm dumbbell stuff, go right ahead.
PS how come you've been a site member here for 3 years and were only now "about to start running the novice program?"
PPS Is my above PS one of the rare cases where the question mark is supposed to go outside the quotation marks? Seems like it might be but I never have full confidence in that. Dammit.