4 years for Dr. Bowers. I have heard 1 year for an appointment for Dr. McGinn and 4 months for the surgery.
I would go to Dr. McGinn's web site and look at the criteria. For GCS they are looking for: compliant with HRT, full time for at least 1 year, change of name at work and work ID ( I change my work ID while waiting for my legal name change), making your HRT doctors schedules, demonstrating a persistent female identity, maintaining therapy appointments, not purging (throwing out your female clothing) and a description of your dysphoria and a recommendation from your therapist. To have GCS you will need 2 letters form a LSW masters degree or higher.
In order to see Dr. McGinn for an appointment for GCS you will need a letter with the elements she defines on her web site.
There are other doctors with different criteria.
So I made sure I was compliant (was doing it anyway) and was able to have it documented by my therapist. My second letter came from my PCP and a LSW there. They are a LGBT (heavy on T) primary care with 23,000 patients.