Congrats on the approval, JMR
I recently got the Discover IT as well (still waiting on the card to arrive), and I'm excited to use it.
I wish I had taken your route just so I could have been using a good, major credit card with a decent rewards program. This Discover IT will be the first major credit card I've applied for (I'm 23). I always associated credit cards with debt (and their rewards as travel perks anyway) and never paid attention to any major ones. I also thought I could easily be denied, so I collected a few store cards since I was 18 to build a good credit history. I figured I would be more easily approved and you typically get a discount on your purchase when you apply at the cash register.
I believe my first was with American Eagle at 18, and I got a $300 limit. I also have Express ($500), Kay Jewelers [for the girlfriend] ($500), Macy's ($600), Lane Bryant [for the girlfriend] ($750), Banana Republic ($1,900), JC Penney's ($1,900), Walmart [for the gas discount] ($1,300), and Kohl's ($1,000).
The Banana Republic card is a regular Visa that can be used anywhere and has a rewards program for Banana Republic and all of its brands. I got to the point of basically replacing my debit card with it to collect the rewards. It took longer than it should have to realize that I might as well carry a major credit card and take advantage of a rewards program that is (1) much better; and (2) doesn't have to be used exclusively on Banana Republic brands. I was in the habit of paying everything in full anyway, so it doesn't cost me anything and I actually benefit from it.
Said girlfriend (now wife), on the other hand, had a much sadder beginning to her credit history. The boyfriend she had before me financially took advantage of her, and she basically just couldn't tell him no. Even her parents completely
screwed her over. She had bad debts (including but not limited to unpaid medical bills) and public records against her. Her wages were garnished at one point. Fortunately, I think the combination of being with me and the two of us moving far away from her hometown for college has helped her become financially responsible. Based on her credit report, the last of all derogatory marks should come off by the end of this year.
Anyway, like you I am in the process of building credit. How I started out didn't hurt me, but I could have gotten more out of a better card. I think my credit score is decent for someone my age (mid-700s). My wife had a rocky start, but is on her way to building a good score. You're positioned well to build up a good credit history. So make the credit card companies lose money by having you as a customer, make the system work for you as much as possible, and enjoy the benefits of being a Discover member!