When your tank stablizes, all of your nitrates,nitrites and amonia should be at 0. Depending on situation and how you STARTED your cycle should be about 3-5 weeks.
Often overlooked is Salinity or SG, and PH. Everyone gets so afraid of nitrate that they forget about the PH and other typical requirements of marine life. Just use the time that your twiddling your thumbs waiting for the biologicle cycle to complete to get yourself familiar with handling PH and and Calcium levels to keep them at spec and you wont put any of your livestock in danger or be caught off gaurd when your PH is down. You will already have experience with buffering and playing with it.
Once your tank cycles for waste removal and so on (the benifitial bacteria reach happy medium) During its life there should be very little changes to the nitrate/nitrite/amonia levels with exception of dirty filters, death of livestock, over feeding and other typical situations you can adjust accordingly with behavior changes- cutting back feeding, adding rock or making changes to design of the layout slowly, maint shedule and attention to tank,and water changes.
Post a bit more detail about your tank and all of your test results, this is much easier to guage than blind speculation.
-Reef