I fishless cycled with 3ppm. Nitrite started to spike about a month later (completely new tank, no bioprimers). Nitrite concentration was 1ppm. Nitrate started building up 2 days after the nitrite spiked. NO3 concentrations as high as 70ppm can easily be observed (depending on the # of water changes). NO2 took about a month to get down to 0 ppm.
So the whole process took about 2 months. Nitrite and nitrate concentrations depend on the concentration of ammonia you use for cycling. 3ppm is a ok, as long as you stock heavily immediately after the cycling is done (otherwise your precious nitrosomonas will start starving and eventually die).
As long as you see nitrite spiking and then get back to 0ppm you are all right.
If you use a trickle filter you should also let time for pseudomonas colonies to develop. In the latter case you should also wait for the nitrate to spike and come down. If you don't have a trickle filter (so no anaerobic bacteria) do some water changes until nitrate settles around 5-10ppm and start adding fish immediately.
If you want, i could send you my cycling tables.