Don't do it! I know a lot of people who trim fan leaves but I just don't think it is a good idea at all. The fan leaves make the energy for the plant. Now trimming branches is a good idea (bottom few branches only!) because those bottom branches are not going to produce sellable bud anyway and you want the plant send that energy to the top branches. Expecially 6 week away from harvest don't stress the plant. You can try to tuck some leaves behind buds if you want more light to the bud site but don't cut up a perfectly ok plant. Now what I do is right before harvest (like 3 days) I do through and trim all the fan leaves and stop watering. But that is just because I find it easier to trim and it dries a little faster that way. Don't just go cutting leaves off your plants, they grew them for a reason.
Also, if I saw a bag of dope and it had fan leaves in it I would NEVER buy it. that whole fan leaves/filler bullshit it a joke, here in the year 2008 buyers want only buds, this isn't the 70's anymore