If they did a complete "Paul Heyman Guys/Girls" faction, I'd start it up around the first of next year or late this year so that all of the various players are there.
Brock Lesnar - It seems likely that, at some point, Lesnar will be challenging for the title. If they want Lesnar as WWE World Heavyweight Champion or challenging for the title during WrestleMania season, have him return at the Royal Rumble to either defeat the champion there or to win the Royal Rumble match itself to earn his spot.
Cesaro - By late this year to very early next year, I expect that Cesaro will be either IC champ, US champ or he'll be the one to unify both titles if WWE decides to go in that direction. If he's with Heyman by December and isn't carrying a title, then I'd say they've lost faith in him.
The Ascension - I'd bring The Ascension up from NXT and have them represent the group from the tag team perspective. They're not established, but that'd sort of be the point since they're a couple of very hungry guys looking to make names for themselves. With Heyman as their "advocate", they'd gain instant credibility in the short term and it'd be up to them to establish themselves in the eyes of the fans.
Paige - I have a feeling that WWE will put more focus on the "Anti-Diva" aspect of Paige's character as time goes by and the fans become more familiar with her. The fact that she isn't tanned, bubbly, blonde and/or doesn't work her body like a pole dancer is a big part of what got her noticed and over in NXT. It's what brought her to the dance down there, so having such a different look and mentality can definitely help establish her in the long run.
These four being in the ring with Heyman and Lesnar simultaneously would be a fun sight, in my opinion. Lesnar has the star power, Cesaro has this aura of potentially being this strong upper mid-card champion who'll make his way occasionally into the main event picture, and The Ascension & Paige would have this sense of containing a mixture of the young & hungry new faces but with a much darker image and mentality. They could all benefit from being a Heyman Guy or Girl.