Originally Posted by Tanic

When wake turbulence is involved, takeoff clearances are predicated on weight class of preceding aircraft (small/large/heavy/super) and the succeeding aircraft. It can be measured in whole minutes 2/3/4 or radar distance, but would not be a short pause. The takeoff clearance cannot be issued until the prescribed interval in time or distance has passed.

As always, the pilot in command is the final authority to operate the aircraft, but could be required to leave the runway for other traffic.