The books will tell you that the majority of people with bipolar disorder go around 10 years before being properly diagnosed. (Just thought I'd tell you what you'll find in the reading.)

Once you get in with a specialist who knows what they are looking for, the diagnosis could come quickly if your symptoms are very clear and follow a pretty predictable pattern. But if your symptoms are more subtle, follow less of a clear pattern, look a lot like something else (depression for instance), the possibility of being misdiagnosed or the diagnosis being delayed for awhile so the doctor can further observe you becomes higher.

I presented as depressed for many years. It wasn't until around 5 years ago that my pdoc felt comfortable calling what I was going through bipolar disorder. He had treated me for over 2 years at that point. He was very careful to observe me over time before he came to that point. But I still present as mostly depressed but go into mixed states several times a year. I present mostly like bipolar 2, except for the mixed states which require at this point that my diagnosis be bipolar 1. It can be complicated. We all present a bit differently so unless you present like a textbook case, it might take some time.