i think thats a bit much. just make sure you dont eat any sugar about a half an hour before you give her oral and youll be fine. ( sugar almost always gives yeast infections)
before sucking on chocha make sure mouth anisepticly clean with listerine
its really neither good nor bad. personally i would be concerned because a lot of women seem to get yeast infections and that would be pretty nasty to get it in the mouth.
and it can be done before, after, or during sex. just like giving head can be done before, after or during sex.