LUKE: You know what I mean, Rory and Jess, Jess and Rory. I think this is great. Don’t you think this is great?
LORELAI: I think Rory’s seventeen and it’s probably about time for a Jess.
Rory’s birthday is in October, and it’s now November, so Rory is actually eighteen now. Her eighteenth birthday apparently passed without fanfare, or her mother even remembering it!
The Annotated Gilmore Girls 