Ann: Special Dividend and Dividend Payout , page-38

If you hold the shares on the close of business 29/4, you will get the special dividend. On 30/4 they go ex dividend, which means anyone who buys them will not get the dividend. However, all things being equal, the sp will probably drop by around the dividend amount on 30/4 opening. Don't worry about the registration date. That is usually 4 working days after the ex-div date to allow for settlement and the registry books to be updated. That will happen automatically. If you own the shares at the close of business on 29/4, the registry will show you as the registered owner. If anyone buys the shares on or after 30/4, their name will not get on to the registry until 7/5, thus they miss out.

Note previous poster's message on 45 day rule if that is relevant to your situation