I'd give the meds now, it only takes about 20 minutes for tablets to disolve in the gut and enter the system. As for her vomitting, and I am speaking from a nurse perspective not personal experience with pets, but maybe it will help. Anaesthetic slows the motility of the gut and makes the whole system sluggish this can last upto 48 hrs. Post op we always advise to start with small amounts of fluids then build up to small amounts of solids ONLY if the fluids are staying down, and to gradually re introduce normal diet over 48 hours. maybe try her with Bland diet later today if she keeps her water down...its a lot gentler on her already stressed tummy
Slobbery wet Lucy kisses for Penny and a for you from me.