Bugsy took one yesterday afternoon, I am guessing around 3pm, and he started eating late at night...
I also force fed him 3-4 times before he started eating on his own, so I am sure that helped his tummy feel better to eat on his own... Aside from that he is on Reglan, which coats the the digestive tract and helps with nausea...
My vet said the appetite stimulant lasts for 3 days.