Hi,
I just heard back from Privilege Club about this,
Please be informed that you can redeem Qmiles/Qcredits for anyone prior to expiry for future travel.
Should you wish to request for date change once award upgrade processed, we can process date change upon collecting applicable charges as per revenue ticket and if redemption seats are available for new travel date, award upgrade can be processed considering same number of Qcredits which were redeemed initially.
However, if redemption seats are unavailable for new travel date, we cannot refund Qcredits, as per Privilege Club policy.
In the case of Gold members, no change/cancelation fees would apply. So it seems a change of date would be possible as long as there are award seats available. I am not sure about changing the itinerary though. I hope this helps in any case.