While meetings in the United States may be called as late as the last minute, Italians like things to be prepared well in advance. In fact, meetings should be scheduled 2-3 weeks prior to the actual event (in writing and in Italian, preferably).
However, arranging a meeting is not a one-time deal; follow-ups to confirm the meeting are the norm. When reconfirming the meeting, follow up either through e-mail, phone, or fax (again in Italian). The most convenient times to meet are usually from 10AM-11AM or after 3PM.
Nevertheless, no matter what kind of meeting you are setting up with an Italian business partner, try to avoid convening in the month of August. Due to the numerous amounts of festivities that month, most businesses will be closed, so plan your business trip accordingly.