Calendars are the only print job where being early is the entire strategy. Walls are a finite resource and they fill up.
Start from the hanging date
Decide when it must be on the wall, then work backwards.
For most programmes that is ‘in the post through October’.
Book artwork for late summer
Grids, local dates, per-branch details and approvals all take longer than expected.
August artwork is a comfortable programme; November artwork is a recycled one.
Build the template once
Shared grid, per-branch headers, local dates as data.
Forty versions stop being forty artwork jobs.
Decide binding by how it ships
Mailing at volume wants a flat saddle-stitched profile.
Anything handed over or hung hard wants wire-o.
Keep the file for next year
Next year should be a date change, not a rebuild.
That is what makes it a programme rather than an annual panic.