It's an exciting day for the co-founders of meal-kit subscription-box company Blue Apron, which made its debut this morning on the New York Stock Exchange. Nearly five years ago, the company was just an idea the three young men were tossing around. In a 2016 interview with CNBC, co-founder and CTO Ilia Papas brought us back to the beginning and shared two important lessons he learned while building the $2 billion startup:

Blue Apron CEO Matthew B. Salzberg stands with co-founders Ilia Papas (L) and Matt Wadiak (R) on Wall St. ahead of the company's IPO on the New York Stock Exchange in New York, June 29, 2017. Lucas Jackson | Reuters

1. Stay focused on what customers want

In August 2012, Papas and co-founders Matt Salzberg and Matt Wadiak got 20 of their closest friends and family members to try the first version of their product, boxing up the food by hand in their New York City apartment. Blue Apron's prototype was a success. "When we decided to do Blue Apron and we told our friends about it," Papas said in February 2016, "it wasn't a very difficult sell. They said they'd wished something like this existed in their lives." Once you know people want to buy your product, maintaining its quality is of the utmost importance at every step, Papas told CNBC, including while your company is focused on scaling.

Matt Wadiak, Matt Salzberg and Ilia Papas, co-founders of the recipe delivery service Blue Apron, pose for a portrait in their offices in Manhattan, NY, on April 19, 2016. The Washington Post/Getty Images

2. Get to work — immediately