Birthday had potential but they pretty much killed it dead with that awful video. It needed a video that could be played on TV channels and showed off the song. Nobody paid attention to the song with the official video.
What it needs is a banner on iTunes. It made MAJOR gains and nearly cracked the top 10 when it was in the hot songs section for a few days.
It's good to have a bit of time before smashes. While I wish Birthday could've smashed it doesn't mean anything. At least we got an amazing bop out of it!