Over that time, Lester spent every waking moment trying to save a 2017 recruiting class that was rated in the top 50 in the nation by nearly every recruiting service. And while a few recruits followed Fleck to Minnesota, it was Lester's job to work around the clock and stop the bleeding.
He turned in a solid performance.
Western added 23 recruits, including 12 three-star players (Scout.com). It has the 76th-ranked class in the country, good for second in the Mid-American Conference behind Toledo (62nd).
"Two and a half weeks and only seven days with the entire staff was obviously a challenge," Lester told The Detroit News. "It was the craziest 21/2 weeks of my life."
Not to mention, Lester had two different challenges on his hands.
His first job was to keep some of the players who might start to waver in their commitment in the face of coaching changes. Lester would have to sell them on his vision.
Luckily for the new coach, many recruits were in town for their official visits on the day he got the job.
"I had a chance to start immediately," Lester said. "I sat down with them and talked about the process here and how special it is. I wanted to make sure that they realized that the reason we're winning is because of the culture we built here, and that's not going to change."
One of those recruits that was always going to be a Bronco was three-star defensive tackle Ralph Holley of Orchard Lake St. Mary's, who is heading to Kalamazoo with high school teammate and three-star linebacker Dwayne Chapman.
Holley and Chapman got in touch right away upon hearing of Fleck's departure.
"We got on FaceTime with each other for an hour and discussed what was going on," Holley said. "We decided that we're committed to the school. I already knew that coach Fleck was on his way.
"The coaches that were here were great people. But the culture and the players here really showed that they were behind this program and really cared about winning for the program and not for the coach."
The people who stayed committed to the university are the ones who kept this recruiting class together, Lester said.
"They're special people and they love this place as much as I do," he said. "They made their decisions for all the right reasons. That's a special group that's going to have a ton of success."
Still, there was work to be done. Lester needed more than just 11 players in this recruiting class. He needed to identify players who could help the program, and building those relationships on such short notice was not an easy task.
"It was getting them here on campus and showing them what WMU could offer," Lester said. "Those 12 guys we added were just amazing.
"The coaches did a phenomenal job of going out there and finding these guys and bringing them home."
Western Michigan recruits
Name Pos. Ht./Wt. School
K.J. Anderson DB 6-0/170 Buford (Ga.)
Trevor Campbell OL 6-5/280 Naperville Central (Ill.)
Dwayne Chapman LB 6-0/210 St. Mary's (Mich.)
Dylan Deatherage OL 6-6/260 Bishop McNamara (Ill.)
Zenden Dellinger OL 6-6/260 Snider (Ind.)
Mohammad Elazazy OL 6-5/310 Menasha (Wis.)
Ali Fayad DL 6-2/230 Dearborn (Mich.)
Reece Goddard QB 6-2/210 Kirkwood (Mo.)
Josh Grant K 6-0/185 Flower Mound (Texas)
Jaylen Hall WR 6-4/165 Macomb Dakota (Mich.)
Treshuan Hayward LB 6-1/210 Ann Arbor Skyline (Mich.)
Ralph Holley Jr. DL 6-2/270 Orchard Lake St. Mary's (Mich.)
Derrick Hubbard LB 6-2/202 Ann Arbor Pioneer (Mich.)
Dez Lance DL 6-2/265 Sterling Heights Stevenson (Mich.)
Ryan Lezzer WR 5-11/190 Clearfield (Pa.)
Tanner Mathias DE 6-4/240 Menominee (Mich.)
Corvin Moment LB 6-1/220 Pahokee (Fla.)
Tanner Motz LB 6-3/265 St. Johns (Mich.)
Tom O'Mara OL 6-3/265 Marist (Ill.)
Luke Sanders WR 6-4/180 Cathedral (Ind.)
A.J. Thomas DB 6-3/170 U-D Jesuit (Mich.)
Prince Walker RB 5-10/180 Montini Catholic (Ill.)