Bringing a plant as healthy as possible all the way to harvest, and chopping when tricomes are full milky, are the best you can do to achieve maximum potency.
You are right about the fact that underfed plants might express deficiencies with fall colours, but not all will react the same. Also, 5 days in soil is a short time, especially at this stage as plants do not require a lot of nutrients. In the 3rd pic, I can see some yellow and maybe some purple hues on some top calyxes..??