Fescue question

I read in an article from UGA that the best time to begin grazing tall fescue is between 4" and 8" of plant heighth and to stop grazing between 2" and 3" of plant heigth. Now it seems to me that since the hay we bale is also used as grazing/forage, this would also be a good rule of thumb or time to start looking at cutting and baling tall fescue. I know it should be baled in the early boot stage before seeding. Is there any correlation between the 4" to 8" and the early boot stage?

Fescue question