The captives are Consuelo Gonzalez, a former congresswoman, Clara Rojas and the boy, believed to be the son of Rojas and a rebel fighter, born three to four years ago.
Celebrity mission
Chavez, who has dubbed the mission "Operation Emmanuel" after the boy, said the move had been delayed as Farc rebels had not informed him of the exact location.
The MI-172 helicopters are being sent by special arrangement with the Colombian government.
International observers are flying with the group, including representatives from France, Switzerland and several Latin American countries.
Oliver Stone, the American film director, and Nestor Kirchner, a former Argentinian president, were also part of the mission.
Luis Carlos Restrepo, Colombia's primary peace negotiator, said that his government gave the mission its full support and would not allow its military to interfere.
Restrepo will join the group in the central Colombian city of Villavicencio, 95km east of the capital Bogota, from where they will be given instructions for movements on Saturday.
The group will disperse and head to a number of potential meeting points given by Farc before being told which is the final destination whilst in the air.
The handover is expected to take place on Saturday or Sunday.
Secrecy of the handover point has been paramount to Farc who distrust the Colombian government they have been fighting them for more than four decades.
Rojas was kidnapped more than six years ago when working as an aide to Ingrid Betancourt, a former Colombian presidential candidate. Gonzalez was abducted in 2001.