Hi Debbiemg and welcome .....
So sorry your husband has been diagnosed with an AN. However, it sounds like you are doing all of the right things by gathering information and opinions.
As for how quickly treatment can be accomplished, much of it depends upon the schedule of the treating physician you choose. Additional factors on the timing are whether you have debilitating symptoms or rapidly changing symptoms, how fast you can achieve insurance approval, etc.
In my case, my first surgery was three weeks after diagnosis My second surgery was three months after diagnosis of regrowth.
As I am sure you have read, typically ANs are slow growing so usually a patient has sufficient time to schedule surgery/treatment when it is mutually agreeable between the doctor and the patient. If you happen to experience a rapidly growing one, most physicians will accommodate an earlier treatment.
Many thoughts and prayers for good advice and satisfying treatment.
Clarice