AK,
The dizziness is an expected s/e with this Rx. You may find eating first helps? Also, it should resolve to a good degree as your system adjusts to the new med.
Usually Buspar has a shorter start up time than an SSRI/SNRI...so you can expect to feel therapeutic effects in about
a week.
I believe the use of a benzo as needed/PRN is okay, but you'll need to ask your prescribing doctor to be sure.
Best wishes on your new regimen! I hope it is just what you need for good management! Keep us updated so we can keep you in support.
S.C.