Thanks for letting us know, Jeff! I have the missing information you were looking for regarding its duration...it ends on September 14 of this year.
Gabi, I don't like to be the bearer of disappointing news for you, but this event is only for Pokemon Omega Ruby and Alpha Sapphire, not X and Y.
I was a little skeptical at first, but I was successfully able to get the gift in both Omega Ruby and Alpha Sapphire.