I'd agree with lots of the other responses.....Looks like your plant has at least 3 weeks to go, probably more. If you harvest within a week or so you're harvest will be less productive.... don't just look at the main colas, look at the secondary ones, a bit lower on the plants. One needs to evaluate trichomes, bud density and size and even the size of the calixes as well. I've had plants of the same strain take as much as three weeks longer than the first to mature. If I were you I'd err on the side of letting them go as long as you can so you can get a realistic view of how they will develop throughout the flowering period.
On my first grow I probably harvested a few plants too soon. 75-90% of the pistils were red but less than 5% of the trichomes had turned amber. On the second grow with the same seed I let them go almost two weeks longer and the buds grew larger, denser and the overall effect was enhanced for sure. These plants had about 20-35% amber trichomes and the calixes looked like they were ready to explode (these are the little pods that the pistils grow out of and are covered in trichomes, they are where seeds would develop if pollenated) .
From my experience shorter plants flower faster and taller ones take longer_ even from the same seed, same strain, same everything. I've also had some strains that have more red pistils than white but less developed trichomes and ones with more white pistils than red but more mature trichomes.
You just need to learn how your strain and growing environment affect the development and maturation of your buds to the point at which you want to harvest them.
Let em go and reap an awesome harvest!