12 Week Old Mini-Schnauzer and I have no Idea

I just got my puppy on Nov. 5. I haven’t even had him for a whole week and I feel like I’ve made the worst decision of my life. He’s a 12 week mini schnauzer. The cutest little face. But I feel like I’m just a terrible dad. I’m hoarding him for two days because I’m visiting my mom, and no pets allowed. Who does that? Who gets a puppy and then boards him 3 days later? Smh. And just looking at my life and travel schedule, I knew a dog would be work and responsibility…I just didn’t know it would change my life so fast and so much. I don’t know what to do. Rehome? Stick it out? And then on top of that I don’t know what to do with him when I get him. And I feel I need to set up a playpen or something and not give him access to all of my apartment living room. And that’s another thing, I live on the 2nd floor of an apartment…getting him down every 5 minutes (that’s what some do the puppy training people say) is not really feasible. Idk yall, I need help or words or guidance. I just feel very overwhelmed and it hasn’t been a week yet and all I can think about is the next 15-17 years.