It's never worked in the morning for me either. My magic time is apparently between 3-5 PM central time and i get 1-2 SB for absolutely random searches.
Late night is always reliable for me, often with 2 -3 SBs for a search. Around 11pm PST, which is 2AM EST. I recommend that everyone do a search or two just before going to bed.
What time? I done about 10 searches each day for the past few days and received nothing.
Every day b/t 9am & noon, whenever I get to the computer. The trick (for me, at least (Thanks Gary for this heads up)) is to click "next" through the search results and usually by page 2, 3 or 4 I'll get the SBs. In the morning I never get them on page one, but still within the first search or two. Today it was search 1, page 4. But, as noted, late at night they will often come on page 1.
FWIW make sure you are signed in before searching. Tested for a few days to see whether or not being signed in had much of an effect. The frequency of SBs didn't change, but anecdotally I never got more than 1 SB on any search. But being signed in I get many more 2s and 3s...
