Based on the information available in the posts made by members who applied in-person at PEO Glasgow it appears that there the payment is taken only after the caseworker has assessed your application. In such case:
1. Take two SET(O) forms - one with your wife included as a dependant and the other without her included - to your appointment.
2. Present the SET(O) form with your wife included as your dependant first.
If the caseworker tells you that your wife is not yet eligible for settlement because she has not yet completed 2 years then you can take one of the following two options: -
a) apply on your own using the second form, or
b) request the caseworker to defer your (joint) application until such time that your wife completes the 2 year period.
Do note that if you opt for b) above then your application will be as good as a postal application.
If you opt for a) above then my suggestion would be that your wife applies for
PBS dependant leave by post before 05-Dec-12 and if the application is not decided by 18-Jan-13, she should request the PBS dependant application to be
varied to settlement application (SET(O) form).
Another suggestion is that you should try to book a (family) appointment closer to 05-Dec-12, instead of attending the 19-Nov one.
A completely different option is to apply for settlement (along with your wife) by post closer to 05-Dec-12.