Translate the following English sentence to French:
"Mr President, just one specific question: when will the debate on topical and urgent subjects of major importance start, given that it was quite definitely and firmly set for 3 to 5.30 p.m.?"
Monsieur le Président, juste une question concrète : quand commence le débat d'actualité qui devait se tenir sans retard possible de 15h00 à 17h30?