[Brekkie]

I think the first Thursday May is seen as the traditional date but it is actually surprisingly rare - although both Margaret Thatcher and Tony Blair came into power with an early May election so perhaps that is why it's considered traditional, but they were the only two elections to fall in that week in the 20th century, with the 1955 election being the only other since the war to fall in May. However since then the planned elections in 2005, 2010 and 2015 all fell on that weekend, and IIRC 2001 was only delayed till June due to Foot and Mouth.

Also politically I think often any changes which may see the electorate feeling like they've more money in their pocket happens in April, so is some logic in going to the polls in the weeks that follow.