If you say happy birthday a day late, it's a belated happy birthday. What about when you say it one day early? Is there a single word fitting this definition?

ร‚โ‚ฌ ha, ha, ha! He did รขโ‚ฌ he did, by jasus ! Wasn't that capital ? and รขโ‚ฌยฆ I've always simply written it happy birthday! but my wife recently said that birthday should be capitalized as well. What's grammatically correct?

What's grammatically correct?