The last election was actually held on a tuesday because the thursday was a public holiday (Ascension of Christ) and having two public holidays in a row was deemed inconvenient.
Als Angel of Death already mentioned, this year there were no elections in the Netherlands on the Tuesday before Ascension Day since we already had an early election last year November.
However, the last local elections (2006) were on a Tuesday, March 7. Every year on the second Wednesday of March, the orthodox Calvinists (the ones voting SGP) go to church to pray for a good harvest that year. Therefore, the SGP requested to have the election one day early. Apart from some voters not wanting to vote (or in the case of civil servants, work) on this day of prayer, there was another reason to move the elections. In quite a lot of towns, polling stations are in churches, or buildings owned by a church. A lot of these were not available on Wednesday March 8.