Premature Congratulator 

Describes someone who gets really excited about something too early/quickly and jinxes you. (Also another term to describe a premature ejaculator.)

Wow! I heard that you might be getting that promotion! That's fantastic! I'm so excited for you! I've already told everyone I know!

Geez! Don't be a premature congratulator or you'll jinx it for me!

Premature Congratulator by Siorse House December 23, 2005

Premature Congratulation 

Where you wish people happy *event* (birthday and such) earlier than it actually is

Premature Congratulation. Mother's day was sunday, I showed up at my moms house with flowers on saturday .

Premature Congratulation by CheeseGames June 3, 2017

Premature Congratulation 

When someone celebrates a windfall or personal accomplishment prematurely and it ends up failing or blowing up in their face. Similar to Premature Ejaculation.

Man 1: "Did you hear about Rick? He had to return that new Mercedes he bought after the Newark deal he thought he closed fell through"

Man 2: "Geez, he should know better about premature congratulation."

Premature Congratulation by LEBRON IN DA HOUSE June 8, 2009