i always check titan tv for lost before, but as a rule of thumb i do 1 minute before (that show before S U C K S) and set it for 2 minutes late
if there's a long episode which i find out before i'll make sure it's padded properly then, it sucks missing the ending of lost but even more so to miss the next week clip!
update: this weeks lost figured out it would end at 10:05 and set itself for that, plus i have my standard 2 minute overtime set. (applause for the 622 for figuring something out)