there is no certain way to tell how long you could leave it without printing before the ink dries up. But in general, any aftermarket ink is of different chemical composition to the manufacturers, so there is no telling how this could react with the design of the printer. Coming from an experienced repairer with mostly epson and canon printers, i can tell you that CIS's will shorten the life of the print head, running extra head cleans to unblock nozzles will fill up waste ink pads more often, and the print quality/colour will be worse than the manufacturers ink. There are some places that will sell you the printer and CIS with a warranty, i would suggest doing that to cover yourself. Canon print heads arent cheap, and Epson print heads arent cheap, and you can't replace them yourself very easily as they are a fixed unit. Even using the proper ink you can get blocked nozzles if you dont use the printer for a couple weeks, but then at least you have not voided the warranty and can get it repaired. I would suggest a cheap colour laser printer instead, then you dont have to worry about any of that crap.