You need to hold the shares at risk for a continous 45 days plus day of purchase and sale (so a total of 47 days). This can be made up of 47 days before after or any combination thereof.
The exception to this rule is if you are only claiming less than $5,000 in franking in the financial year...in which case you can hold it for less.
(check with your tax advisor in case someone is going to try to class this as advice).
EXS Price at posting:
69.0¢ Sentiment: Buy Disclosure: Held