I've always thought conception days were more important than Birthdays. The day you popped out is completely arbitrary.
The real thing to celebrate is winning THE GREAT SPERM RACE!
So 9 months before my birthday, I celebrate CONCEPTION DAY (OBSERVED)!* It was on THAT day my parents decided to forego the blowjob / blumpkin / whathaveyou in favor of a maximum ball draining splooge in the cooge, allowing this little spermie to make it ALL THE WAY to that lovely egg. It rammed the shell with all the gusto of a raging stallion, and BURST through to the other side, creating the HOTfusion that would end up divining me through the pineal lightning rod! EPIC SPERMATAZOICALIZED VICTORY!!
Birthdays? For suckers.
CONCEPTION DAY IS FOR WINNERS!
*For simplicity's sake, 9 months prior to your birthday is acceptable. If you know the night you were conceived, well, you're closer to your folks than I.