Going off certain foods, and smells, is definitely one of the first symptoms, but morning sickness is a tricky thing, some do, some dont, could just be feeling sick, or could be gut wrenching agony, either way, you will know it when it turns up.
We are all different, with my first I had no early symptoms, with my second, I couldnt look at ham, it looked like absolute putrid rotting flesh, and that was at a few days late. Only advice I can give is dont force yourself to eat if you're not hungry, just nibble on crackers, or biscuits, maybe fruit, but keep hydrated, and your body will take the lead.
Congratulations, and hope it all goes well, good luck KiwiPanda