Harvest?

I am 40 days into flowering. Two strains (Indica) and appears the Sativa will take two weeks longer. I have several large Kola;s that are more mature than th e 5branches below (Indica). I have heard I can harvest them first and then let the others marure more (same for the sativa). How can I tell the optimum time to harvest and my understanding is I just hang the plants upside down. Any Input? Also when do I cut nutes, use just water and stop watering altogether (in days)?

Here ya go. Everything you need to know about harvest time:

https://www.rollitup.org/newbie-central/936-when-harvest.html

you need a 30x or 40x magnifying glass (i just got 1 of each on ebay for $4 each ) when your trics are cloudy and a few amber start to flush when there 50% amber harvest what is ready and leave the rest for a week or so, you can give them molasses but no nutes for that last week if they look like they need nutes.