I'd say make a few tests before that. Check how long it takes for your food to leave your stomach. For some it's relatively fast (a couple of hours) but for some it can be longer (since I got dysautonomia and gastropariesis, it can sometimes take more than 10 hours to leave my stomach...).
Vomiting (+ being found) is the main failure risk of SN : you don't want to mess that up.