L.S.
Honestly, you may want to start making appointments now if you are considering getting a feel for a doctor. With my first child, I used my existing OB even though I didn't like her (long office waits and other issues). There is no way to know if you are going to like the office and the personnel if you don't try them out first. ALSO, considering there are long waits, you may not even be to get the doctor you want once you are pregnant (some offices don't accept new patients regardless of whether you are already pregnant or not).
Good luck!
L.