Firstly, that's great that it's almost gone in only 2.5 days. Secondly, how almost gone is almost gone (like .25ppm?) ? If you're still seeing ammonia, then the nitrifying bacteria have something to metabolize. I usually wait until it shows 0, and then dose it daily to keep it slightly above 0. Others on here tend to dose it back up to 4ppm each time; both, in my opinion, are correct ways of doing it. The 4ppm route will allow for a larger bio-load upon stocking, at least.
Congratulations on having the patience to fishless cycle...you will thank yourself in the end.