About 9 p.m. a week from Sunday, at least two of the men who want to be president of the United States will sit down in Baltimore's convention center for the first nationally televised debate of the 1980 campaign.

Edward Hanna, in charge of the Baltimore debate, said yesterday he is confident all of the details will be worked out "two or three hours after the debate is over." From Hanna's comments at a press briefing, it's clear he has a long way to go.

The starting time isn't set, although it probably will be either 9 p.m. or 9:30 p.m.

Hanna and League of Women Voters' officials don't know yet who will be chosen to ask the questions. In fact they don't even know how many panelists there will be.

They have decided that the debate will last 90 minutes -- unless, that is, President Carter cahnges his mind and decides to join Ronald Reagan and John B. Anderson on the convention center stage. A three-way debate would last at least 30 minutes longer and maybe more.

Despite Carter's firm refusal so far to take part unless Anderson is excluded, Hanna said the league still hopes the president will change his mind.

One of Hanna's biggest problems will be dealing with an expected crowd of 1,500 to 2,000 reporters, writers, photographers and television crew members. CBS is the only network committed to televising the entire debate.