Colour developer and fixer will likely be the first components to go bad, whereas stop bath and bleach will last for a very long time. Since colour chems are expensive, and test strips are dirt cheap, I'd say give these chems a try and see whether they still work. You know what the leader of properly developed C-41 film looks like, so you could develop the leader (one half fully exposed, other half unexposed) of some test roll and see how it turns out. Bad fixer is easy to detect by its yellow precipitate and possible yellowing milkiness, and you could replace fixer concentrate with TF-5 from Formulary in case.
Care to tell us which brand chems you are about to get?