The system gets a little tricky and difficult (flexibility-wise) when an operator is designated as a QCC. The only time that a call will overflow from the QCC is when it is in position busy - which is how you currently have the AutoAttendant set up. If the QCC doesn't go into pos-busy then all calls are just going to sit in queue there.
Here's my suggestion: Make a new calling with the transtalk as the only member. Put that transtalk in a coverage group and apply that coverage group to the QCC operator. Replace the vm calling group against the QCC operator with the new calling group that you just made. Use night service to trigger the auto-attendant. If you have the MLM set up to follow the system mode - change it to follow the business schedule and modify the business schedule to match your office hours. This way the day and night greetings will play at the proper times, regardless of whether the system is in day or night mode.

Functionality: When the QCC is in position busy all calls will queue to the calling group which has the transtalk as the only member. You can even set up this calling group to overflow to the auto attendant should callers wait too long. Calls that ring directly to the transtalk's extension (not calls to the calling group) will queue to the QCC if not answered. When the system is in night mode calls will ring to the auto-attendant and the business schedule in the vm will determine whether the day or night greeting plays.
That's about the best I think you're going to do with being setup as a QCC. If you changed the operator position to a DLC you'de have some more flexibility.

Hope this helps.