Cooldown on talented CL is 3.5 seconds. Cast time on LB is 1.84 seconds (will drop to 1.75 seconds when I start using the spell haste totem again). 1.75+1.75 = 3.5. Should work out perfectly into the rotation.

In the OLD system, CL had a 5s cooldown, and required an additional LB. But not any longer...