I listen to the Dave Ryan Morning Show http://kdwb.iheart.com/media/podcast-dave-ryan-show-podcast_drshow/ sometimes. On the 16th, 17th, and the 21st of February, Fallon talks about going from brunette to blonde. Her appointment is booked for the 28th.
Fallon talks about her hair starting at the 27 minute mark on the 16th, around the 50 minute mark on the 17th, and at 29.50 minutes on the 21st. I haven't listened to anything past that yet, but I'm sure that they will continue to bring it up until after a few days after Fallon gets her hair bleached and trimmed.