I think its common sense, and prudent, once you have fans on to wait for 150deg before takeoff. To do otherwise is outside the limitations. Once the fans are on, you are stuck with lower limit as I understood the temp sensor is not at the friction surface. Therfore the indicated temp may not be the actual temp in the critical zone.
I dont turn them on on the turnround for exactly that reason. Even 350deg will be 200-250 after 20-30min turn and taxi.