If it's only four bottles, I'd sample one a month until they tasted good, then finish the rest.
If it's four gallons, I like what @hd4mark said as a starting point. If, after a month or two goes by and individual bottles are still bad, I'd free up bottles for other batches as needed, but still give some of the bottles time.
edit: posted 30 seconds after @Mojojojo replied. Too lazy to edit the reply further.