Please answer a question about the following article about Korean War:

On 7 June 1950, Kim Il-sung called for a Korea-wide election on 5–8 August 1950 and a consultative conference in Haeju on 15–17 June 1950. On 11 June, the North sent three diplomats to the South, as a peace overture that Rhee rejected. On 21 June, Kim Il-Sung revised his war plan to involve general attack across the 38th parallel, rather than a limited operation in the Ongjin peninsula. Kim was concerned that South Korean agents had learned about the plans and South Korean forces were strengthening their defenses. Stalin agreed to this change of plan.

When did Kim Il-Sung call for the Haeju conference?
1950