I just had an adventure appear in Dungeon ("Throne of Iuz," Dungeon 118).
Here's the timeline as I remember it:
Late December 2003 -- Submit first query letter with adventure details. Disclosure form included.
January 2004 -- Send check-up letter with query letter and disclosure form attached
A few days later -- Get approval to work on adventure.
Every month thereafter -- Send updates explaining progression of adventure.
May 2004 -- First draft submitted with maps.
Early July 2004 -- Got detailed note from James Jacobs on changes needed. Includes need to rewrite the entire opening, add some monsters and attach Greyhawk angle.
Early August 2004 -- Return with second draft. With appendix on needed reprints from Sword & Fist, Monster Manual II and Stronghold Builder's Workbook.
Late September 2004 -- A few additional questions trickle in from Jacobs. Response sent out immediately.
December 2004 -- Publication.
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That's a long timeline at first glance. But you should remember that I work a full-time job, welcomed a new baby into the family and went on two vacations in that time. I also submitted my first and second drafts in the middle of convention season.
Likewise, articles queries submitted in November and December have to fight through Thanksgiving, Christmas shopping, Hannukah, Christmas and New Year's celebrations -- all of which trigger a TON of vacation time in every industry. Give it time.
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My previous two adventures had varying times:
"Buzz in the Bridge" (Dungeon 110) -- Submitted in September 2003, Published in Feb. 2004.
"Racing the Snake" (Dungeon 105) -- Queried in September 2000 (I think) and published in October 2003. Now that's a loooong time. I think it went through three editors.