Hey Styxx...without wanting to be Mr. Depressive here...but are you sure that it is already the right time to get the voice actors?
We made a bad thing at TBP. The voice actors were recruited about months before the scripts were sent out. It lead to the point that quite some actors were gone, once the scripts were ready.
Another thing....I suggest to start voice acting, once ALL missions are done. While our scripts were sent out, one of our missions needed some restructuring in the messages...so we had to rerecords. Believe me...start this acting thing later...it WILL safe you time and headache....I have my experiences with it...others from the TBP team will confirm that...