Query on options. If i were to buy gggob options today at say...

Query on options. If i were to buy gggob options today at say 3c.
If i choose to on sell them later obviously they are treated as a normal cgt event.

What happens in the instance i want to convert to ordinary shares prior to expiry, sept 2018. Say i pay 8c to convert my options purchased at 3c. Total cost 11c. Theyre worth, say 20c. Not a cgt event i presume.

The main question is what happens then upon selling the shares which i had converted and cost me 11c? What are the critical cgt dates (october 2017 purchase or sept 2018) and prices (purchase price 11c or 20c) for assessing tax liability?

I cant find an answer anywhere. Anyone know?