Ily S Z.
I usually write in my journal just before going to sleep. This is a great time for reflection on the day and reflection in general as your mind is not crowded with the day ahead or tasks at hand.
I do it twice- both at the start and end of the day. In the morning I wrote my to do list and in the evening I review the day.
I write in my journal in the morning simply because that's the time I could make work for me. It's usually right before I start work. Sometimes a little earlier, like over breakfast.