You are doing very well!
You are now at the start of the middle phase, waiting for FC to hold at 15 overnight. As you are already doing, it is most effective at this stage to focus most of your chlorine additions in the evening. During the day most of your chlorine will be lost to sunlight, instead of working towards the conversion. In the evening almost all of the chlorine works towards the conversion, so that is the most effective time to add chlorine (now that you are in the middle phase).
You are now at the start of the middle phase, waiting for FC to hold at 15 overnight. As you are already doing, it is most effective at this stage to focus most of your chlorine additions in the evening. During the day most of your chlorine will be lost to sunlight, instead of working towards the conversion. In the evening almost all of the chlorine works towards the conversion, so that is the most effective time to add chlorine (now that you are in the middle phase).