I think you are taking the right approach: if you are at 60/40 milky to clear trichomes, then continue with your grow and keep monitoring the trichomes. And while I, like you, love some cool colored buds, when the trichomes get to where they need to be, chop them down (after 48 hours of darkness) regardless of whether the lower buds have turned purple or not.
When you are thinking that it is time to harvest, please compare the density of the top colas with the density of the buds lower down on the plant. You can harvest in stages; cut the top buds and start drying those while giving the lower buds some more time to fatten up before they get harvested. Given this is your first harvest, you may just want to chop it all at once and save tinkering for a future grow. Obviously, your call.
Regarding your question about hanging buds for drying, I'll again suggest going to YouTube. I'm a huge fan of Mr. Canuk's Grow, and he has several short videos on his YouTube channel dedicated to harvesting (as well as harvesting, drying, trimming, and curing). BillWard420 also has a video on harvesting, drying and curing. Oh, these vids are both focused on autoflowers by the way. Grow Your Own with Kyle Kushman has a ~3 minute video on drying and curing though it isn't dedicated to autos, but Kyle is a legend regardless.
If you have some monster colas, you may want to cut those off and hang them to dry by themselves, whereas if your plant is made up of a lot of decent size buds, you could choose to cut the plant at the base and hang it whole. Keep in mind that hanging a whole plant will result in longer drying times, which isn't necessarily a good or bad thing, but the longer the dry time the more careful you need to be about the potential for mold growth; make sure you have good air circulation when drying, but don't point the fans directly at the buds.
My contractor is here finishing up the drywall on my new grow room, hanging the security door, etc. Man, looking at your plants is making me even more eager for the room to get finished so I can pop some seeds!
What with 2020 being the year that it was, your harvest will be a great start to 2021!