Trent Harmon's Wise Words for the 'American Idol' Finale's Winners and Losers (Exclusive)

The former 'Idol' champ opened up to ET about his best advice for everyone who wants to make it in the music business.

With the first season finale of the American Idol reboot kicking off Monday night, former Idol winner Trent Harmon has some advice for everyone who is going head-to-head in the finale: be ready to hit the ground running.

"What I told them is, 'This is all gonna be over in a week. It's all gonna be over. Whether you win or lose, you need to have a plan for the morning after the show," Harmon recounted while sitting down with ET's Sophie Schillaci on Monday. 

"Every song idea that comes into your head is a potential cut on your record that you're gonna put out one day," he added. "That conversation's coming. So be ready the day after your show, whether you win or lose."

Harmon -- who recently released his first album, You Got 'Em All -- won Season 15 of American Idol in April 2016, with fellow contestant La'Porsha Renae coming in as the season's runner-up. But even after the win, Harmon says that it's still a difficult journey to becoming a music star.

"If you end up in Nashville, you're not just going to walk into a publishing house and go, 'Hey, here's my [Idol] trophy. Please give me some songs,'" he said. "It will help you to a certain extent, but at some point, you're gonna have to take a pen and a piece of paper and write a song idea down and put it out into the world."

Harmon said he "wasn't necessarily worried about that" the night he won the show, and he wishes that he would have "been on top of it just a little sooner."

"I took, like, a week [off], not long, but like a week, and I could have been writing down some inspiring songs during that week," he lamented.

However, Harmon admitted that he actually found himself in a creative lull.

"The truth is, after I won Idol, I didn't have any good songs," Harmon shared. "So I spent the last two years writing the album, which makes it even more special for me."

Harmon's debut album, You Got 'Em All, is out now.

ET caught up with the musician following his big Idol win, when he remained calm and collected in victory.

"I understand and I'm fully aware that all that happened tonight was it got me into the bottom of the next level," Harmon told ET. "I'm gonna keep that mindset until further notice."