Is my love interest really interested?

So theres this guy whom I've had a crush on since elementary school. We always had common friends and knew each other but never had any kind of relationship. Then, around the end of freshman year we began talking to each other as friends, but I moved and got involved with someone else shortly after. Fast forward 3 years, I found him on fb last week and decided to add him. He wrote me right away and seemed flirty and really excited to talk to me. I gave him my number & we've been text messaging each other every day (well, mostly very late at night). We've made plans to hang out and he seems really excited to do so; the problem is that he supposedly works every day for long hours & the one day he has off in the next few weeks is the day of my best friend's graduation, so I can't bail on her,nor bring him along. I've suggested other days, but he always says that as much as he really honestly wants to hang out with me, his schedule is unpredictable (and he doesn't want to leave me hangin). Also, he takes around at least 20 minutes to txt me back most of the time, and other times he won't write back until I send him another message a few hours later. He always responds with a very apologetic message explaining how busy he was. This confuses me because when we do talk, he seems really really into me, but he's always (literally unbelievably) busy. And I'm against making all the efforts because I don't wanna seem too clingy (which I'm not) or too into him (which I am. lol). I also don't want to not make an effort because if he really IS busy and trying to give me attention, I don't want to be a brat about it. How do I go about this? Do I just wait it out and continue making the first effort? Is he playing games? By the way, I'm 19 and he's 20. I'm in college & he works at a loading dock-type place.