cgt dates

I’ll like some guidance on discount CGT dates?

I bought Coalworks shares on 22 Sept 11 and they were compulsory acquired by Whitehaven Coal. The bid period ended on the 4 Jul 12.

For CG discount purposes, do I use the end of the bid period or the cheque payment date? (Which I’ve not received yet)

As part of the takeover deal I was given Orpheus Energy shares.

Is the date of acquiring Orpheus share for tax purpose considered as the date I purchased Coalworks?

I expect someone will point me to the relevant tax ruling but I would like their understanding of the rule.

My experience with the ATO is they don’t explain but reiterate what you have read.

Thanx,
Radicool Views