Thats a fast drop in ammonia! what
test kit are you using?
If you are cycling the tank, I would only get the ammonia upto 2 at the most, not 5.
Check your nitrites, if the ammonia is falling you should start to get readings for nitrites.
Keep the ammonia between 1-2 by adding ammonia daily. Once the ammonia and nitrites fall from 1-2 ammonia to 0 ammonia & 0 nitrites in 12hrs the cycle is complete. do a 100%
water change and stock the tank.
A 60lt tank will take 4-5 weeks to cycle
Keep the temp at 30c during the cycle