It was building over months of time, and they dropped subtle hints along the way that Bischoff was turning NWO.
First, the night of Bash at the Beach 96, he's missing and doesn't do the pregame show with Dusty, shows up the next night on Nitro with no explanation about his whereabouts when Hogan turned.
Then on the August 5,1996 Nitro, Bisch is missing again and doesn't do hour 2 of Nitro with Heenan as everyone wonders what the hell is going on, and if he's been attacked or kidnapped.
8/12/96-Heenan asks Bischoff straight up where he was last Monday and Bisch says he doesn't want to talk about it.
Early September, Bischoff agrees to the stipulations at War Games that if the NWO wins, WCW pays the "bills" and they get their own segments on WCW Saturday Night, entitled "NWO Saturday Night" (which is gold, BTW). NWO wins and on Nitro the next night Tenay and Heenan ask why would Bischoff agree to such terms and more speculation abounds.
9/23/96 Nitro-all of the WCW guys are in Japan except for Savage, they jump him and beat him down, and take over the rest of the broadcast, holding Bischoff at the announce position against his will, or at least it looked that way.
9/30/96 Nitro-Bischoff starts out Nitro with an angry anti-NWO promo and says he has to "take care of business", leaving Schiavone and Heenan to announce for the night as they wonder what he means.
10/14/96-Savage heads to the ring for his match with Mike Enos when Bischoff stops in the aisle way and says that he must show Savage footage that is urgent, it's Elizabeth crying and saying she still has feelings for Macho. Savage loses his composure to the point of near-tears as he leaves the arena. Heenan/Tenay wonder why in the hell would you show Savage that footage so close to Havoc and his World Title match with Hogan?
10/21/96-Savage heads to the ring to face Chris Benoit, but is dressed in street clothes and Bisch stops him again, with some more footage of what is really going on, it's Hogan on the set of the 3 Ninjas movie holding Elizabeth against her will in a movie trailer and to "make Savage believe". Savage sounds like he's on the verge of murder as he leaves with the words "Life is fragile".
10/28/96-Footage is shown of Piper's debut at Halloween Havoc, and Bischoff says he's committed to trying to get Piper to sign a contract with WCW.
11/4/96-Bischoff supposedly took a trip to Portland to get the match signed with Hogan and Piper, as he wasn't on that Nitro, as negotiations were close or were they?
11/11/96-Bischoff says things don't look too well, but a video was sent to the production offices at WCW of Piper singing and in the background the marquee said "hogan vs. Piper", which gave the impression that things were looking up in terms of getting Piper to WCW.
11/18/96-Bischoff addresses the fans and says he's doing everything in his power to get Piper into WCW, and is interrupted by the man himself Piper, as he looks nervous as hell and is called on his B.S, before Piper could ring his neck, the nWo fill the ring and all chaos breaks loose as Bischoff is revealed as the latest member of the nWo.
I think there might be some little things I may have forgotten, but that seems like the jist of it.
