3ppm,4ppm,5ppm,6ppm, doesn't matter in the early stages of a fishless cycle, all of those would provide plenty of ammonia for the ammonia oxidizing bactera (Nitrosomonas, we call them A-Bacs for short here on the forum.) You've already done the right thing removing some water to make sure its not 7 or 8ppm, which would enourage the wrong species and perhaps set your cycle back.
The "Day" designation will not really have started until the first day you put ammonia in, although its possible a little of that food started to convert and gave things a tiny bit of a pre-start. We seem to see a lot of fishless cycles that finish up between 60 and 70 days. But its different for each tank and pretty much entirely unpredictable, probably hinging on the chance number of Nitrosomonas and Nitrospira bacteria that have happened into your tank from your tap water.
The reason you want to be doing all this work to create a working biofilter is that ammonia, even in tiny amounts causes permanent gill damage, shortening the life or killing the fish. Likewise, nitrite(NO2), attaches to the fish blood hemoglobin protein and destroys it, causing suffocation, with the immediate result of permanent nerve damage, leading, like the ammonia, to a shortened life or to death. For many species of fish, the turning point levels are a quarter of a part per million (0.25ppm), which can happen very quickly even with a few fish in a tank with no working biofilter.
Its only after you really get into the hobby that you begin to realize that the filters are really a "kit" and don't work when you buy them. The skill you are learning hands-on will be valuable to you all the rest of the years you do the hobby.
~~waterdrop~~