Well, first off, you're about to get a drove of replies saying why even flush? Flushing is kind of a personal taste thing, some people claim a much better smoke when they flush starting two weeks before harvest, some claim their buds get much bigger never flushing and continuing to nute till the end. Personally I like to flush once about 3-4 days before harvest. If I were you I would try to flush a few and try something else out on the other, and see what YOU prefer.
Now it sounds like you're kinda unsure which plant is which and finishing when. Time to bust out a magnifying glass (They have a great 15x magnifying glass at radio shack, as well as a 60-100x but thats too much magnification for me) and start checking your trichomes. If you want to start flushing the normal 10-14 days out, look for mostly cloudy trichomes and maybe a couple of amber ones. Most people like to harvest when the ratio of cloudy tric to amber is about 80:20. So when you see something like 95:5 ratio of cloudy to amber, you're probably ready for a flush.
