How far in advance can cartridges be prepared?

I know this probably sounds like a silly question, but how far in advance can cartridges for any modelgun be prepared in advance? Can an individual have stocks of "pre-loaded" cartridges ready weeks, or even months, in advance prior to using them, or do they need to be used immediately after preparing them; is there a "shelf-life" to them as soon as they (caps within the cartridge) come in contact with silicone grease (based on Cerwyn's loading instructions)? Ideally, I'd like to have batches of them ready in advance, but I'd rather not find out the hard way that not using them within a few days or even weeks would cause the cartridges harm. I tried to search this sort of question, but couldn't find an answer...

Based on my limited experience - caps worked in MGC and Marushin cartridges even after about a year in storage.
I did not check open or Hudson ones (with hole), where the cap is exposed to external air.

So far I only had problems with some boxes of 5mm caps that did not fire correctly, but they had problems even "fresh" after purchase. Usually when a box of caps worked consistently after buying, it worked after storage too.

I spray silicone instead of using more solid grease, not sure if it makes a difference in shell life. It could be that this dries out quicker and performance is not optimal for stored cartridges, I just don't know for sure.

As long as the loaded cartridges are stored carefully and kept dry there shouldn't normally be a problem.
I tend to clean my cartridges immediately after firing, then after a tumbler polish (as described elewhere here) I'll load them up.
The silicone grease I use is relatively dry so there's little chance of getting the caps wet.
Using oil, either silicone or light machine oil might well run onto the cap during storage and cause inevitable missfires. Smoke effect is better I think when using oil sparingly for lubrication rather than grease. So if oil's used I would load up just before firing rather than risk dissapointment

Loaded cartridges are stored in their original boxes and then into a big plastic storage box which keeps them good and dry.

Months go by sometimes before they're fired, and I have very few failures. Loading can be time consuming especially if you fire 100 -200 at a time as I often do. Having them pre-loaded saves a lot of valuable firing time.

Thanks Cerwyn and Smootik . What you both said was what I was expecting, but I wanted to double-check before I got underway.