I think it's safe to say that the "workup" you'll get varies depending on who you are seeing and where.
Most people who "discover" a heart problem do so first through an ER visit. Common tests are a chest x-ray, EKG (measurement of the electrical impulses that drive the ehart to pump) and usually an MRI. Most ER facilities may also perform an echo if they know you've got a heart condition however the technician doing the echo may not be all that strong in charting valve issues (or congenital defects) and a second echo might be ordered later on by a cardiologist to be done by someone who really knows how to do it, what to look for.
After an initial stabilization of your condition, you'll probably have a cardiologist who will oversee your progress, evaluating and treating your condition medically, not surgically. At some point surgery is probably going to be in everyone's future and you'll be given a few suggestions on where to go, who to see.
In my experience, it was the surgeon's team that evaluated me and my condition. I got a whole battery of tests including blood work, ECG, echo's, stress test, CAT scan, MRI, a cath, and another form of echo done to evaluate the health of major vessels throughout my body. My evaluation was actually what they put most heart transplant candidates through. It was done at the Cleveland Clinic which was really the best (and only?) choice for me given my set of circumstances. After that transplant evaluation, they opted to try and either repair my tricuspid valve which was failing dramatically, or replace it with an artificial valve. There was no discussion about a homograft or any other form of treatment, just artificial St Jude's valve...
My case was fairly "special" in that I had an exsisting heart defect called transposition of the great vessels (something I was born with) and had already had one OHS to repair that, about a year after I was born.
I don't think there's a set process or series of steps one goes through from the moment they learn they have a valve problem to when it gets repaired/replaced. It really dpends on the kind of care they're getting from their doctors, how that care progresses, the developement of the problem and response to treatment.
It isn't like, "First you'll get an x-ray, then an echo, then an MRI, then a holter, then a cath, then surgery."
I had a number of these tests AFTER surgery too. In fact, the first time I ever had a holter monitor was well after surgery, about 18 months after because I had some "pesky" arrhythmias which were creeping up at night when I was getting ready for bed. They've since cleared up on their own for the most part.
Everyone's progression from initial diagnoses to a "final" treatment will be different.