I think the longer you wait the happier you'll be with the results. Go ahead and harvest some side branches in a couple of weeks for two things- have more room and you can see how the high will be after you dry them a few days. Personally i would let the main cola and the interior branches ripen up another month.
I'm going by Mr. Muddy's sticky up at the top of this forum to harvest my grow. Three of my plants now have the bottom leaves turning yellow.
"One of the most frequently asked questions is how do I know when my autos are ready to pick? The convention wisdom from growing photo period plants was to watch for color change in the trichomes, or crystals. For an uplifting high, harvest when the trichomes are all cloudy, for more of a stone, wait till a percentage have turned amber. Sound advice, for photos. But autos are a little different. While some strains have shown amber trics, many do not.
So how do I know when they are ready? I watch the the fan leaves. Over the past several years of growing autos I started taking samples at various stages of growth to evaluate the high. I tend to prefer my smoke with a little stone so began to leave them longer than the 8-9 weeks that are advertised. I find that around 11-12 weeks the plants are ripe for me. I also began to see a correlation between the color of the fan leaves, the color of the trics and the high/stone quality of the smoke at the various sample intervals. It seemed that the greener the fan leaves, the more clear trics the buds had. As the fan leaves started to yellow and die off, the trics became less clear and more milky. By the time that all the fan leaves had died off and the bud leaves were starting to yellow, I got the quality of smoke I wanted. At that time most of the trics were now milky with no, or only a few, clear ones. Here are some examples:"
https://www.autoflower.org/index.php?threads/when-to-harvest-autos-your-leaves-will-tell-you.4889/