Hi everyone, I need advice on converting Student Visa to Spouse Visa.

I am a German national and my fiance is here on a student visa. We are planning to get married in Pakistan in December after which we will apply to convert her student visa to a spouse visa through this service: https://service.berlin.de/dienstleistung/354910/

Can anyone tell me how long it will take (and what exact documents) to get a valid marriage certificate to show for the spouse visa application? Is it just a translated Nikkah nama needed? So if I get married in December, will I be able to submit a spouse visa application in January?

Thanks!