Published time is 8-1/2 minutes for D76 1:1, for diffusion enlarger (read the fine print in the Kodak literature on their web site). For my condenser enlarger, I use 7 minutes as my standard time with 6 vigorous inversions every 30 seconds. With moderate to bright light this yields negatives that print well on an Ilford 1-1/2 filter. For very bright light I may reduce to 6 minutes; for dim light I increase accordingly to say 9-10 minutes.
Prior to adapting this agitation method, I suffered uneven development with Plus-X in D76 1:1. The edges of the negatives near where they ride in the stainless steel film roll holder would be thin (under developed).
For some reason, I get more even development with Tri-X in D76 1:1, especially in very bright light despite the vigorous agitation. These comments are for 120 film in Mamiya C330 or Rolleicord equipment.