Detective Conan is a notoriously long-running series -- it's been running for like fifteen years, and hundreds of cases have been solved. Conan has made friends, received upgraded technology over time (cell phones!), and has generally "kept up" with its audience.
Yet, logically, time in-universe must have passed, and Shinichi's continued absence should be more notable than it is if he's been gone for more than a year.
How much time has passed, currently, in the Meitantei Conan universe?