If it's not getting shot then the CLP will effectively last "forever". Clean/Oil it again in 6 months when you take it to the range if you like.
In reality, you could probably go forever without cleaning it. That's probably not an ideal way to care for a gun. But it's probably been done that way a gazillion times. And in reverse, there were plenty of military artillery pieces that were literally dripping with grease during their existance on land/sea/air based installations. Both extremes likely did their intended jobs just fine.
Oil doesn't "evaporate". It may change molecular structure if exposed to extreme heat/pressure/shear forces. But sitting in a bottle or on the surface of an unused bearing or between two pieces of metal, it will retain it's properties for at least a few hundred human lifetimes.
Oil probably will never seep into primers in modern cartridges, and surely not in the light usage you're doing. Every rookie cop hears about some old guy that never cleaned his model 10, never took it out of the holster. He just sprayed it with WD-40, loaded, twice a year. Then he went to fire it that one day in his career that he needed it, and it didn't fire. That might be a wivestale but it's told in every LE academy.
Really, don't worry about it all much. Put a little CLP on/in the thing once in a while. Get out and shoot it. If you can't, get IN and dry fire it.
Sgt Lumpy - n0eq