I think every one feels overwhelmed after they get a puppy. I know I had a moment of "what did I do??!" But I can honestly say that I fell in love with him the moment I brought him home - we had a connection.
Yes my life would probably be easier in a lot of ways without him, but he makes up for it in what he gives me. To be honest, my life would be so boring without him. He is my partner in crime.
If you feel you can't give this pup a good home, then give him back now. Don't wait until he becomes attached to you and then make him leave.
That would be very unfair.
Also, not everyone is going to feel an instant connection with a new puppy. Give it time. I've heard of some people that could barely stand their puppy until they reached 6 months old or so. They loved them, but didn't have that connection...
So give it time, or if you KNOW it's not going to work out, send him back now.