Countdown Vigil is the period right before a transfer when the channel is in hard need and essentially "watching the clock" (though Simes don't use mechanical clocks). Usually, the channel is accompanied by the assigned Donor, and goes apart into an insulated room to just wait out the remaining time before the transfer is authorized.
It is important to time a transfer exactly so that the next transfer assignment will be "in step" with the next assigned Donor. The matrix pattern of timed transfers goes Tecton wide and keeps channels and Donors of compatible speed and capacity in step with one another. One accidental miss can strain the schedules for hundreds when there is no slack in the staff.
From: Unto Zeor, Forever, Ch 18. 'Watching her gather and focus the ragged remains of her strength into that demand, Digen hadn't the heart to oppose her. But he said,"I really don't see what good that could possibly do. I don't keep countdown vigil." '
From: Sime Surgeon ' ...Digen said, "Ever since my accident, I stopped keeping countdown vigil. I get morbid and start wondering if this transfer really will be my last like the physicians keep telling me. You wouldn't want to take on a client in that condition, would you?" '
(Source: Index card file. Sime Surgeon http://www.simegen.com/sgfandom/rimonslibrary/surgeon/SURGEON1.html) Time just before a transfer, when a channel's friends --- who are also channels --- stay with him. May hold a vigil party. Digen says he doesn't keep countdown vigil.