Hey man -
Pistils are the worst indicator of when to harvest, don't use them - I have a plant going now, 20 days into flowering that just started getting orange pistils while still pushing out white ones. Pistils are just a sign the plant is looking for pollen still and orange pistils are like women in menopause.
Trichomes are the best indicator for a controlled harvest, see GA6's post above for how to read trichomes - to do this you will need a "loupe", they come in different strengths, 40x is the starting point for trichomes - 60x being ideal. This is the loupe I use -
http://compare.ebay.com/like/320951819071?var=lv<yp=AllFixedPriceItemTypes&var=sbar
If you can't afford a loupe or can't wait for it to come then pay attention to the plant, these three indicators (all together) are usually a sign of time to harvest:
#1. Low ratio of white pistils
#2. Yellow / dying off of lower leaves on the plant (lower leaves must die first, then top leaves to meet this criteria)
#3. Buds look "creamy" white
If all three of those line up together it's a sign of times to chop as well, but a loupe is your best bet. Even Radio Shack sells the microscopes for like $15.