How far in the future do you need to be thinking to make sense of the world?
I can imagine some calendar-centered routine that starts with "I'll need that for tomorrow" and works its way out slowly through time into a year from now. To the extent that you can do something now in advance of needing to do something in the future (distinct from planning to do something in the future) that seems reasonable.
How much think-ahead time is helpful?
It's almost certainly worth 15 minutes to plan 24 hours ahead of time, and almost certain worth 60 minutes to plan 7 days ahead. I can make a good argument for spending 1 day to look ahead 90 days.
Think ahead or do ahead?
Hey, I should send postcards this vacation.
Here's a list of people to send postcards to.
Here's a deck of postcards, already stamped and addressed, waiting for the opportunity to write a note.