According to Parliament's regulation (article 141) the government can call for a vote of confidence from Parliament with either a written or an oral statement by the prime minister.
The proposal is registered in a special daily agenda and the discussion begins two days after its tabling, unless it is requested to begin immediately, as is the case today. It lasts three days and on midnight of the last day a rollcall vote is held.

The government enjoys the confidence of Parliament if it receives the absolute majority of the deputies present, which in no case is permitted to be less than two fifths of the entire number of deputies (120).

This means that following Wednesday night's statement by Prime Minister George Papandreou, the discussion will probably begin on Friday, immediately after the swearing in of the new government, and will be concluded at midnight on Sunday with the open rollcall vote.