This is the data I recorded for the fishless cycle I did in Jan 2016
Because this tank is 26 litres and has just one male betta and one small nerite snail, I initially added ammonia to just 1 to 2 ppm as this is more than enough for that bioload. The colour was between 1 and 2.
Day 1 - added ammonia Stage #1
Day 4 - no change
Day 7 - no change
Day 10 - no change
Day 13 - no change
Day 16 - ammonia still same but just a hint of nitrite though still well below 0.25
Day 19 - same as day 16
Day 21 - ammonia still showing between 1 and 2 and nitrite the merest hint. Got frustrated and did a 100% water change then added ammonia to give a reading between 2 and 4 ppm.
Day 24 - ammonia between 1 and 2, nitrite 0. The ammonia dropped from 2 - 4 to 1 -2 but no idea where it went.
Day 26 - tested after 2 days because getting fed up. Ammonia 1 to 2. Nitrite merest hint.
Day 28 - ammonia 0.5 nitrite > 5 (off the top of the chart). Added ammonia to ~ 3ppm Stage #6
Day 30 - ammonia 0, nitrite >5
Day 32 - ammonia 0, nitrite >5. Zero ammonia on 2 test 2 days apart, added the one third dose of ammonia. Stage #8
Day 34 - ammonia 0, nitrite >5
Day 36 - ammonia 0, nitrite >5. Zero ammonia in 2 tests 2 day apart, added the one third dose of ammonia Stage #8 again
Day 38 - ammonia 0, nitrite >5
Day 40 - ammonia 0, nitrite >5. Zero ammonia on 2 tests 2 days apart, added a one third dose of ammonia. Stage #8 again
Day 42 - ammonia 0, nitrite 0. Added a 2 to 4 ppm dose ammonia Stage #10
Day 43 - ammonia 0.25, nitrite 1.0
Day 44 - ammonia 0, nitrite 0. Added 2 to 4 ppm ammonia. Stage #10 again Then power went off for 4 hours.
Day 45 - ammonia 0, nitrite 2 - was the cycle affected by the power cut?
Day 46 - ammonia 0, nitrite 0. Added ammonia to 2 to 4 ppm Stage #10 again
Day 47 - ammonia 0, nitrite between 0.5 and 1. Added ammonia to between 2 and 4 ppm Stage #10 yet again
Day 48 - ammonia 0, nitrite 0. Finally stage #14
Ammonia and nitrite both zero 24 hours after adding full dose ammonia = cycle finished.
As you can see, ammonia finally dropped on day 28. And nitrite dropped from off the top of the chart to zero between days 40 and 42.