When should I harvest?

Looks like 2 weeks give or take, but you're better off going by the trichomes. If it's sativa, more like 4 weeks.

If they've been in flower since July they should be done, and judging from the photos all the pistils have already turned and if your seeing amber trichomes I pretty sure most of them are already cloudy/milky, it's time to harvest. I'd let it go two weeks just to make sure the buds aren't going to gain any more mass then chop it down. Hopefully, I answered your question and remember Happy Growing and Free your mind one puff at a time.

Thankyou, I feel like the buds aren't as big as the should be. I used the zoom on my phone camera and from what I can tell some of the little trichomes have started to darken a tiny bit. But just wanted to confirm with experienced growers before I go cut it down.

Those look beautiful, and 8 - 9 weeks is probably expected for flowering in general, but that is not the only thing to reflect on. I would check the trichomes with a jeweler's loop or a magnifying glass. If 80% of trichomes are cloudy with some amber you should be in the sweet spot (generally speaking although some strains don't necessarily apply to this rule. If they are still mostly translucent you should give them more time in my opinion.