I tested SAM Broadcaster LITE and I wonder if this software can do démarer AUDIO files (programs) to an exact time.
I never heard of an audio file format called demarer and I'm pretty sure SAM doesn't support this.
Because right now my tests show me that the audio file is placed in the rear, and therefore can not start the specified time on the program.
If you're talking about the position in the Queue where the tracks are put, simply change your schedulin rule from ipBottom to ipTop or from QueueBottom to QueueTop.
If this is about the position INSIDE the track, open the Song Info Editor and go to the Settings tab in order to verify the correct cue points.