I'm reading a fascinating book called The Accidental Diarist: A History of the Daily Planner in America by Molly McCarthy. I was especially interested in the very beginnings of what we would call a planner. Back then it was used more as a memo book and to record expenses.
The earliest forms of them were from the mid 1700's and had a dated weekly format that is similar to a Moleskine weekly notebook, with dated spaces on one side and the other ruled for financial tracking.
This article has photos of a similar book, from 1796. These little books were meant to be carried with you at all times to record expenses and make note of significant events of the day.
This time was before the big diary boom of the 19th century when keeping a diary was fashionable on both sides of the pond. These little memo books were less about personal reflection and more about straight record-keeping, although according to the book some personal reflection did occur.
I'm fascinated by these beginnings of planners! I would love to see something like this in person.