Fudge, who has recently been sacked, catches the Prime Minster up on the developing Wizarding War, then introduces him to the new Minister for Magic, Rufus Scrumgeour.
The exact date of this visit is impossible to determine. We know that Sirius Black died on June 18, which has to have been a Thursday in Harry's world because it was the fourth day of the second week of OWL exams. Fudge tells the Prime Minister that the wizarding community was calling for his resignation for a fortnight. The community learned of Voldemort's return on the Sunday following the battle, which would be June 21. Two weeks later takes us to Saturday, July 4, at which time Fudge says he was sacked three days ago. We'll place the sacking on July 1, then, and this visit on the 4th.