Machar announced the date in a letter to officials monitoring implementation of a peace deal signed in August.
He had refused to return to Juba until it was demilitarized and a number of his soldiers were allowed to deploy there for his protection.
Kiir removed Machar from his post as vice president in 2013, aggravating political tensions which deepened rifts between Kiir’s Dinka ethnic group and Machar’s Nuer group. The feud flared into a civil war that has killed tens of thousands and forced more than 2.3 million to flee their homes.
U.N. officials have repeatedly warned of dire food shortages and spiraling inflation in South Sudan.
Doctors Without Borders President Joanne Liu wrote an open letter Thursday stating that “On top of this already dire humanitarian situation, an additional and preventable medical emergency is unfolding,” citing a “nationwide lack of essential medicine.”
With the rainy season fast approaching, disease outbreaks and muddy roads could present more problems for aid agencies. Presently, 2.8 million South Sudanese require emergency food to survive.