Another sign of TV’s reality recession: CBS’s new dating show 3 had its official time-slot premiere Sunday night and ended up scoring what appears to be the lowest demo ratings ever for a premiere on the network. Per Nielsen, the show averaged a mere 0.5 rating with adults under 50 and just 1.7 million viewers. The show held on to less than one third of its Big Brother lead-in and tumbled nearly 40 percent from a preview episode that aired Thursday. Expect CBS to either shift 3 to Saturdays or cancel it altogether, possibly by day’s end.