Mini Cycle

[fragNplug]

I have upgraded my tank to 180 gallons, used all my old sand and old rock from difrent systems and moved all my livestock.
I expected a mini cycle but this seems pretty big to me.
tank has been up for one week, i did one 20% water change to get ammonia low again, as well as now im using prime.
ammonia is now .50
(false reading im sure as i used prime to change the chemical makeup of this ammonia. )
nitrites are 0
and nitrates are less then 5ppm
im curious as all my fish are here for the cycle should i keep doing water changes or keep using prime what is safest for my fishys.