Dont get too stressed by the colour, Im almost always very very very dark but drink 3/4 litres a day so definitely dont need more water. A lot of people never show in the pink at all but are in ketosis
I just use mine when I want a wee. Not every time, maybe once a week, or if I've felt especially hungry/icky that day, just to check I'm still in ketosis. I doubt time of day really matters, since you should be in ketosis at all hours.