There’s no known way to measure fat-adaptation, so it can only be determined subjectively, but there are a few indicators. First, let me point out that ketosis begins almost immediately after carbohydrate intake drops low enough, because serum glucose and insulin drop, and insulin is the main regulator of ketogenesis (although glucagon plays a role as well, under the right circumstances). The process called fat-adaptation is a cellular adaptation to metabolizing fatty acids in place of glucose and even ketone bodies, thus sparing the glucose and ketones produced by the liver for the organs that require them.
At two months in, you are probably fat-adapted. Part of fat-adaptation involves mitochondrial healing, part the ramping up of the production of some hormone or catalyst, the name of which I forget. Dr. Phinney has a great description of all this on the Virta Health site, if you can find it. I forgot to bookmark it, myself. But these changes take time, which is why fat-adaptation lags behind nutritional ketosis. One useful marker is that people who exercise notice a drop in performance when they embark on a ketogenic diet, and once they reach fat-adaptation, their performance returns to pre-keto levels, and sometimes even exceeds that.
Otherwise, you’re left with a sense of energy and well-being as your primary markers. People occasionally find they need less sleep, so they might find themselves rising before dawn and cleaning the house or working in the yard, for example. Or they might find themselves taking up exercise (shudder!) to have something to do with all that energy.
You can explore how much additional carbohydrate is safe for you to eat above the 20 g/day limit, but we advise waiting till fat-adaptation for that. Where exactly your carb threshold lies is individual and depends on how insulin-resistant you are, for one thing. How advisable exceeding the 20 g/day limit might be in your particular case would depend on whether you are a sugar/carb addict, how well you feel, how much you miss some particular carbohydrate-rich food, and so forth.