Board of Directors has declared a cash dividend of $1.25 per common share for the first quarter 2013. The dividend is payable on April 26, 2013 to common shareholders of record as of March 20, 2013, with an ex-dividend date of March 18, 2013.
So when is the best time to sell and get paid dividends for somone who already owns shares, March 20th pre-market?
The ex-dividend date is taking into account the 3 days that it takes the stock to settle. This is why it is called "ex dividend". In other words, it is the day on which your stock will be too late to collect the dividend on March 20th.
It you are the owner of the stock on March 15th, you will be the "shareholder of record" on March 20th which is 3 business days later. You are safe to sell on March 18th if you like.
The ex-dividend date is the date you care about. If you want to collect the dividends, the earliest you can sell is the ex-dividend date.
This said, if you are planning on selling, you may want to sell it on March 15th (the last trading day before the ex-dividend date. The stock price will open down the $1.25 dividend on March 18th, so the net is the same, but you don't have to wait for the dividend to show up...
optionjunkie88 is correct. If closing price on March 15 is $33.00, expect an opening price of about $31.75 on March 18. I *generally* prefer to hold the shares long-term, due to the tax implications. Dividends are treated as ordinary income, which in my particular situation is better than short-term capital gains. Your mileage may vary.