if you do cycle using fish..bio spira helps as long as it is good. you may see a slight increase in ammonia but it should go away pretty quickly as well as a small spike in nitrites..usually the spikes are pretty small.
you can also use media from an existing tank.
or a hardy species like zebra danios.
if you do , it is important you monitor the water parameter(ammonia,nitrite and nitrates) . you may need to do water changes if the concentrations gets above .25 ppm (20 or more for nitrate).
with a fishless cycle you still need to monitor so you can log the events and know when the tank has cycled.