You also are supposed to hold the stock for 45 days to get the...

You also are supposed to hold the stock for 45 days to get the franking credit.

There is also a risk if you buy the share on the day before it goes ex div ( in the case of westpac, this friday ).

Some instos are in the habit of failing to settle on T+3 for sales on the last cum-dividend date. If the insto sells to you on Friday, fails to settle on T+3, and settles on T+4 instead, then the share registry is late being notified about the transaction, you won't be a shareholder on the record date ( next Friday ), and you won't get the div. The insto will be required to compensate you for the cash amount of the div, through your broker, but the insto gets to keep the div from Westpac AND they get to keep the franking credit.

ASX colludes with this shady practise.