Cycling a tank can take anywhere from a couple weeks to 8 weeks depending on what method you use to cycle. I have never used fish food to cycle a tank so can't offer any advice.
My preferred method is to do a fish-less cycle using clear household ammonia and the API Master test kit to monitor the water parameters and for me it usually takes about 6 weeks. I keep a chart to monitor ammonia, nitrite, nitrate and pH and test at the same time every day but during the first couple weeks only test for ammonia as that is the 1st step in the process.
If I am in a hurry to get a tank ready, I have used Start Smart Complete which is a bottled bacteria product and just follow the instructions. Or I move a mature filter and media to the new tank and stock with fish lightly but still monitor the water via testing in case a water change is needed.
You haven't mentioned if you've kept an aquarium before so I'm not sure how familiar you are with the cycling process so let us know. ?