Please note that my expertise is in the genres and subgenres of rock, singer-songwriter, synthpop, and the like. This answer may be different for EDM, hip-hop, or country artists.
There's not really a "best time", though Spring through Fall do tend to be the most popular times to release music. (May/June through Sept/Oct). Times to avoid would be the holidays: Late November (because of American Thanksgiving) through the New Year tend to be really slow for releases because no one is really paying attention due to the holidays. So while I'd say there's no tried and true best time, aiming for Spring through Fall is likely your best bet.