prime time 
noun
The time at which a radio or television audience is expected to be at its highest: the show is networked at prime time [as modifier]: prime-time television...
- The study, carried out by Leicester University, found that alcohol appears every eight minutes in prime-time television soaps.
- But those seeking a shift to higher-quality programming on prime-time television are likely to be disappointed.
- Lots of other reporters were arriving at this early hour for their prime-time spots.