Why tomorrow?
A) Nifong's ego can't take anymore abuse ~ and it's only going to get worse from here on out; B) Nifong has want he wanted, a job for the next 3.5 years and retirement (at a rate of pay much higher than he would have had as an ADA); C) pressure from above.
Take your pick - I don't think there are any wrong answers....
Specifically, Friday is the day to release bad news, so it hits the weekend news when fewer people will hear it.