I don't want to sound like a critic but your plants look really stretched out,
how many watts did you have them under and how far away was the light?

As to your question about whether you should harvest; harvesting depends on
the trichomes. The best way to check the trichs is with a 10x to 30x microscope.

This is in the Grow FAQ "When to Harvest" by Zandor and it should help you out:
Quote Originally Posted by Zandor
The colors of the hairs are only part of the cycle of the plants life. They change color by temperature and maturity at the end of their life cycle. The only true way to know when to harvest is to view the trichomes with a 10x to 30x microscope. Mature trichome looks like a golf ball sitting on golf tee, big and round on the top. The color is clear to cloudy. Cloudy is peak for that trichome. Because there are millions of trichomes you need to harvest on the average. They will continue to mature through the drying process for a day or more. Amber color is past prime for that trichome so you are just looking for an average.

100% Clear is week quick head high and will not last long.

100% Cloudy is heavy stone and will last longer (start of peak harvest)

80%/20% Cloudy/Amber is pure peak harvest heaver head and couch lock stone will not last as long as 100% cloudy but is stronger. Anywhere in between is fine and up to you.

Amber Trichomes are dead or dieing. If you pick at 100% amber then you have past prime and the quality of the effect is degraded.

When you check them it's best to harvest on the average with in your field of view and by checking on several parts of the plant and not just one or two places.