help! new snake owner with a fragile hatchling

[Hebii]

I just got an unplanned for, baby corn snake. Yesterday I went to the Petco to get dog food, and since I had time, I went over to see the reptile section. There was a tank with three corn snakes. Two of them were doing great but the other one seemed to be exceptionally small. Even though I really didn't like supporting Petco, I didn't want to let him die so I bought the snake and took him home. (He's a beautiful snake ) The thing is, I never had a snake before. I more less don't know about much on how to care for a three week old hatchling that is undergoing its first shed. I was wondering if anyone could give some advice on what I can do for the little guy in the next few days and how to help him shed?

To be safe, I asked the Petco employees when the snake's feeding schedule was and when they last fed him. They told me the track record said Thursday, October 16 which was over three weeks ago. Then they said they've fed the three snakes every thrusday with frozen pinkies and that the track record was just not updated. Should I trust them and wait till Thursday or should I feed it earlier than that? I'm also worried how his feeding response will be if they really didn't feed him for such a long time.

The shedding just only adds to the problem of feeding. I looked online and found that snakes don't usually take food in the middle of a shed so I won't be able to feed him until afterwards. So far, he has only shed past the head. The skin that came off was tattered too. Do snakes usually kick off the skin in one go, or do they shed the head part first, wait a few days and continue?

Another thing is that many people have told me to leave the snake alone for a few days first after moving to a new home. If I leave him alone for now, would him be able to complete his shed on his own? He ins't moving very much either. Is it because of the heating or is it something else? I'm currently sing a medium heating pad from "All Living Lhings" that covers half his tank Is that enough for him if I using a 5.5 gallon terrarium? Where I live, room temperatures get around 68 F at night and 70 F during the day. Would it be too cold for him at the cool side of the tank?

As a side note, I don't know any vet nearby that specializes in reptiles. At the same, I would really like to settle things down by Thursday Nov, 13. That day would mark a month that he has been fed if assuming the track record was true. I'm worried about the little guy; I want him to live a happy life, but I don't know how to help. Any advice would much appreciated!