Sources have told CBC News that the Conservative government requested that the event be moved up to Friday morning.
The province is set to provide Toyota with a grant worth $42.1 million, while the federal government will pledge a loan worth $58 million. Toyota itself is investing $421 million into its operations.
The announcement is scheduled for 9:30 a.m. ET at the company's manufacturing facility in Cambridge, Ont.
Gary Goodyear, Minister of State for the Federal Economic Development Agency, will represent the federal government, while Economic Development Minister Brad Duguid and local MPP Kathryn McGarry will represent the province.
Toyota recently announced its Cambridge plant would switch from manufacturing the popular Corolla sedan to mid-sized vehicles and higher-value vehicles.
CBC News reported Wednesday that Prime Minister Stephen Harper could visit the governor general as early as Sunday to ask him to sign the writ to kick off the election campaign.