You might find this helpful:
http://www.runningwritings.com/2012/03/injury-series-uncovering-role-of-hip.html
The best treatment for runner's knee is a combination of quad and hip abductor/external rotator strength exercises. Stretching your quads and your calves may also help, but the big two are the strength exercises. A lot of people neglect hip abduction and external rotation strength, and it hampers their recovery.
Since this is often a biomechanical problem, you can take as much time off as you like and it will still hurt unless you address the underlying issues—one of which is poor hip strength causing improper hip rotation during running. As your strength improves you should find yourself capable of running further and further until you start getting pain (which is when you should stop). So maybe after a week of exercises you can do 2-3mi easy until pain, so do that, then stop. Another week and maybe you're at 4mi or 5mi. Etc etc.
If 3-4 weeks of daily strength exercises for the hips and quads don't clear it up (yes, building back strength can take that long) it might be worth your while to see a physical therapist who specializes in gait analysis. Occasionally people can have biomechanical problems not rooted in a lack of strength. There are a lot of "hacks" out there so you gotta ask around to find someone who actually knows what they're doing.