Nice to see you made good progress. Awesome work!
For FC levels and when to add, it is up to you as long as you don't go below the minimum too often or for too long.
Personally I don't like tip toeing the minimum level.
Also, my preference is to add chlorine in the evening and here is why. I bump my FC in the evening to 8ppm and and it will stay at this level all the way until morning, so that is a solid 10 to 12 hours. If I were to add chlorine in the morning, then the 8ppm level would be sustained in the water for a very short period of time because of the sun.
I look at it as an additional safety net, plus for my daily routine, evenings work better.
In the end, the most important thing is to pick the schedule, stick with it and don't let the FC levels drop below the minimum levels. How it is done is not really relevant.