Its while they are on your team. Because i think the skill is call motivator(i could be wrong), but YOU, the head coach, are motivating YOUR players, so its while they are on your team...i have had great results with this skill.
The skills i buy 1st, are all the skills that are TEAM related. Like the offseason, and regular season semiars, ambition, advanced playbook trainging, charm, charisma, motivator,educator,...e.t.c...you get the picture. I make sure that when it comes to my offensive and defensive coordinators they have the skills i dont have, that relate to there side of the ball. For example on offensive, run block and pass block disipline, and on defense, improved blitzing.....things like that. When it comes to position coaches, i focus more on strength, play learning, and intangibles.