From June 2009 to 24 hours before signing day back in February, the former Dallas Skyline product was all but set on going to Texas A&M.
But then something changed.
"It was just me talking to my family and some of the peers I look up to, just trying to figure out what was best for myself and my family in the future, just listening to them and hearing them out and just taking heed in what they were saying," Nelson said.
Ultimately he decided the better choice was to come north instead of south.
"I was able to [say], ‘Okay, I can put Oklahoma in front of A&M because this is better. This is better,' and, you know, be mature about the situation, be mature about my decisions," Nelson said.
Recently he had to be mature about another decision.
Should he play in a position at linebacker where he'll get more playing time or one behind a season veteran in weak side linebacker Travis Lewis where he'll see the field a whole lot less?
"I actually did make the decision during the summer to play behind Travis Lewis because I felt like he can teach me how to play in this Oklahoma defense," Nelson said. "And I felt like learning from him, I'll be able to become a better player, so I decided that that was what was best for me."
It's something that's already worked out."It's a blessing," Nelson said. "It's very valuable to learn from Travis day in and day out. When we're working together, working hard together, he's always constantly coaching me, studying, just teaching me new, different techniques, different schemes to run on defense. It's very amazing, and it's a blessing to be able to play with him."
The other day, though, his role in playing behind him very quickly almost changed when Lewis went down in the second quarter against Utah State in the season opener.
He said things got pretty frantic on the sideline.
"At that time, I was just looking at the ball carrier, and I didn't even see Travis," Nelson said. "And the coaches were calling my name. They were like, ‘Corey, Corey.' And I was just looking around. I had my helmet on and everything, so I was ready.
"But at the same time I was like, ‘What, what, what do you need? What are you calling me for?' And they were like, ‘You need to get in. T Lew's down. Get in. Get in.' And at the time, I didn't even know he was hurt, so it was kind of surprising."
That moment really hit home with his role and the same thing the coaches have been preaching all along, every backup's just one play away from stepping into a huge spot.
Nelson said a lot of things ran through his mind.
"Wow, is this really happening? Am I about to get in the game? Like it just showed that like the coach really trusted me, and I was just excited. Like wow, I can't believe this is happening," Nelson said.
Sooner fans and Nelson alike need to believe it because he's a talented guy that's going to play a key role in some big games, if not this year, certainly in the future for the Sooners.