I'm not doing it this year but in years past I would create a calendar. I would add a show topic idea for each day to the calendar. But that was it for planning. I'd be sure I had at least 2-3 points to make with that topic and then just turn the mic on.
I usually found that by end of the first week a show format would emerge on it's own.
Sounds like you had a loosely organized plan that allowed for the serendipitous to develop your podcast's vibe naturally.
