CAD v CADo, page-234

It can depend on how you bought the shares ...
Eg my online mob tell me this to convert oppies ...............

To exercise a Equity Options contract, you need to notify us prior to 4.20pm Sydney time for it to be exercised on that day. We will only accept verbal instructions to exercise the contract. We will then notify ASX Clear who will randomly determine which writer will be allocated to the trade.

Cheers ....... and just a bit of a hint T65 ...... hit the Google and indulge in some DYOR ....
especially if you are considering following some "Guru" advice that you have read on some site and they are buying XXX mill shares in blah blah blah ..... if this game was a horse race, the stewards would be very busy !!! lol ........ good luck to ya mate