Time: Il est vs C'est à

Three things to internalise. One: Il est X heures states the CURRENT time. Quelle heure est-il ? — Il est dix heures. The il is a dummy subject (like English "it's 10 o'clock"). Two: C'est à X heures states the time of a SCHEDULED EVENT. Le film, c'est à 20h. La réunion, c'est à quelle heure ? The à is the preposition meaning "at". Three: French uses 24-hour clock for schedules in writing (20h, 22h30) but 12-hour with qualifier in speech (huit heures du soir). Half past is et demie (after the hour); quarter past is et quart; quarter to is moins le quart; minutes after the half-hour use moins X (dix heures moins dix = 9:50).