There is the dilemma of writing in the morning. On the other hand, it might be hard to come up with a topic to write about straight out of bed. There isn't anything to write yet about the day and it might be hard to come up with anything creative at that time. The most prominent candidate in that case is to write about what happened the day before.
If you leave it until evening you probably have more ideas to write about. But then you are tired, anxious to just get it done so you can go to sleep. And then, it's again most likely about the day.
For me, the morning routine when I commute to work is the best. It gives me enough time to think before writing without yet cluttering my mind with all the new things. But I haven't gotten it work on these days when I don't commute.
Writing just out of the bed doesn't work too well as I started earlier. Leaving it to the evening results in more boring texts. And postponing it for a while, doing it after going through all the news and interesting articles poses the problem that after all that reading I have too many ideas to write about.