Elections were due to be held in mid-2016 but President James Michel, facing a revolt within his ruling party Lepep ("The People" in the local Seychellois Creole language), announced earlier this month that presidential elections would be held ahead of schedule.
The polls had been due to begin on November 19, but the commission said opposition parties had complained they did not have enough time to prepare.
"We listened to the different political parties, notably the new ones, and decided the vote should be fair," the commission said.
Residents of the so-called "outer islands" will vote on the first two days, followed by the "inner islands" of Mahe, La Digue and Praslin, home to around 90 percent of the country's 90,000 inhabitants.
Michel intends to run for a third and final term against a disorganised opposition, but observers say a run-off is possible for the first time since multiparty politics was re-introduced in 1993. If it goes to a run-off, the second round of voting should take place one to two weeks after the first.