Test Ammonia, NitrIte, NitrAte levels and post them.
You want to be able to "track' the cycle, the rise of Ammonia levels then a drop as NitrIte rises and then falls...
When Ammonia and NitrIte are back down to 0 and NitrAte level rises your cycle is coming to an end...(actually it doesn't end but is continuous, just without the Ammonia and NitrIte "spikes")
When the cycle is "over" and levels stable for a day or two, then do a 25-30% water change and start the skimmer.