Upfronts
1. In the North American television industry, an upfront is a meeting hosted at the start of important advertising sales periods by television network executives, attended by the press and major advertisers. It is so named because of its main purpose, to allow marketers to buy television commercial airtime “up front”, or several months before the television season begins.
In the United States, the major broadcast networks’ upfronts occur in New York City during the third week of May, the last full week of that month’s sweeps period. The networks announce their fall primetime schedules, including tentative launch dates (i.e., fall or midseason) for new television programming, which may be “picked up” the week before…It is also the time when it is announced (by virtue of not being on the fall schedule) which shows are cancelled for the next season.
…Upfronts in Canada are similar but occur in either the last week of May or the first week of June, after networks have had a chance to buy Canadian rights to new American series.
Source: Wikipedia