"The Temple of Elemental Evil" 1e
1st month - read and re-read the module, make whatever changes I feel are necessary, write a script for specific encounters (with variations for theme)
2 - 4th month
I would map out each level on 1" grid, design walls, dungeon dressing, etc. and collect minis to represent the monster and major NPCs.
5 - 6th month
Mount a scale village of Homlett on 4x8 plywood.
7- 9th month
Secure appropriate amounts of 1e PHBs, pencils, paper and other needed gaming supplies to include character record sheets.
10th month
Secure a large enough venue to play and begin interviewing prospective players( to ensure commitment, maturity, etc
11th month
Pre-game meetings for character creation, house rule discussions, Q&A, getting to know each other as a group, etc. Make music selections to accompany proper moments in game, go to the studio and compile any really groovy sound effects that will enhance the mood.
3 weeks out - contract catering (Hell if I've had this much time, I just as well go all out) for the weekend, secure rental agreements for refrigerators for the hall (if none are available.)
2 weeks out - rest and re-read notes
5- 3 days out - begin setting up the hall (again if I knew ahead of time, why not make sure I have time). Decorate to period if possible, set up sound system
2 days out - follow-up with contractors to ensure plans are in place. Secure "crash area" supplies for those 30 minute sleep breaks
1 day out - nothing
Game on!!!
Wish I actually had this lead time - I usually try and do all this crap with about 2 weeks between sessions - obviously, it has never been
quite right.