The announcement came despite Khartoum's rejection of proposals drawn up by the mediators of the East African Inter-Governmental Authority on Development (IGAD).
"Round about August 10 we should be on our way," Kenyan Foreign Minister Kalonzo Musyoka told a news conference in Nairobi.
Kenya is chairing the Sudan sub-committee of IGAD.
The proposal called for two separate armies and central banks in the north and south.
Mediators also suggested that Islamic law should not apply in the capital, Khartoum.
Sudanese President Omar Hassan al-Bashir angrily rejected the proposal, saying IGAD mediators should "dissolve them in water and drink them".
But Musyoka described the row as a "minor setback", saying there was no alternative to the IGAD peace process on the Sudan.
SPLA has been fighting the Sudanese government since 1983 over religious freedom, oil and ideology.
Around two million people have been killed in the war.
On Wednesday, SPLA leader John Garang said the war would only end after Khartoum's acceptance of the IGAD proposals.
Asked if he believed the two parties genuinely wanted peace, chief mediator General Lazaro Sumbeiywo said he did not think negotiators were not serious.
"We think they are negotiating in good faith and good will but they do not maybe have the authority to make the decisions," he said.
IGAD consists of the East African states of Djibouti, Eritrea, Ethiopia, Kenya, Sudan, Uganda and Somalia.