When your chakras start opening, it changes your perception and how you see the world. Once I reached the fourth (heart chakra) I started seeing the world how it really is. It's the same thing as the stages in alchemy. It turns your life into chaos, and then slowly puts you back together. I just reached the fifth last week:)
The signs are different for everyone, but if weird things like strange coincidences, seeing the same numbers on clocks and everywhere else, and the sudden desire to start meditation or praying and interest in religion are good hints.