At 0.5 ketones I would say you are and/or have definitely been in a state of ketosis.
The fact that your reading dropped to 0.2 in the morning likely reflects the dawn effect where the body manufactures glucose to get the body going.
I typically run 0.8 to 1.6 with the highest readings toward the end of the day in the late afternoon, before my single large meal. My ketone levels are always the lowest early in the morning.