I have a late-night tonight. Well I'd rather it isn't a late night and if I was doing the planning it wouldn't be, but I'm not and therefore I know that it is going to be a late night.
This means I either fake my timezone (been there, done that), write a fake private entry and fix it later (ashamed to admit that I have done this too), or write earlier in the day so that I don't miss the midnight deadline.
When writing earlier than I am ready I am forcing myself to do something I'm not really in the mood. I don't have a subject other than not wanting to be doing this right now, but find myself doing it anyway.
And that is the whole point. If you are going to get better at writing it is by doing it every day, whether you want to, whatever the other challenges there are in your life. Turn up and write some words, about what it doesn't matter. It's the process of taking some ideas and converting them into the written form in the hope that if you do it often enough you will get better at it.
— Done —