Laura,
I was lucky and also felt pretty good on the day of chemo. For your first chemo if you're feeling anxious just eat what you feel like. As has been suggested getting your fluids in is the most important thing. I boiled a bunch of eggs in advance. That way I could get a protien fix without having to prepare or smell food the first couple of days after chemo. Chemo often effects your tastebuds, for me just about everything tasted like dirt. I guess it was a blessing as I was able to drink vegie juices etc (which I think already taste like dirt) and at least they are nutricous. Weirdly the only thing that I craved was marshmellows. Not exactly loaded with vitamins!
Through 7 months of chemo I would have maybe a day or two each cycle when I felt a bit nauseated. I never vomitted. They really have excellent medicines to help keep all that under control.
All the best.
Anna