When do I need to submit GST on un-earned income?

[accounts31]

The example being we are selling tickets (which include GST) for a future event.  From my reading the double entries are 1) Credit Bank Account, 2) Debit Unearned Revenue.  When the event is happend I can then credit Unearned Revenue and Debit Earned Revenue. 

The question I have is when would GST be liable given I collect GST upfront but only recognise the revenue later on.   Also keeping in mind that there is the ability to cancel tickets (albeit with the loss of a % of the ticket). 

[accounts31]

Think I may have answered my own question, but still keen to hear from others:

From the ATO website.  Accounting for GST on a non-cash basis 

Sales

You account for the GST payable on the sales you make in the reporting period in which you issue a tax invoice or receive full or part payment, whichever happens first.

This means that if you receive a payment before issuing the tax invoice, you must include the GST amount in the reporting period in which the payment happened, even if it is not the period you issue the invoice