From my experiments - As niyazpk mentions, quality is more important than timing. A poor article will always sink, and most of the time a great article (proper

From my experiments - As niyazpk mentions, quality is more important than timing. A poor article will always sink, and most of the time a great article (properly promoted) will rise. However... - To give your article the best chances, post in the european morning. Why? - The european crowds are generally more discerning, and there is less noise (à la TechCrunch) during the american night. - If you can get a decent number of upvotes from the european crowd, chances are you'll still be high on the front page by the time the US HNers come in. - Already having 50-100+ votes generally will translate in even more upvotes once the US crowds come in. That's been my observation, in general. That said, the difference is not really worth worrying about too much. The main difference is that an evening submission requires a little bit more promotion.