Well if he isn't eating, it means something is not right. Looking at the picture of the cage, first thing I see is you got heat lamps where a snake can get to them and burn himself. Next is what are your temps on the cool side, hot side and you really should offer the same kind of hides for warm and cold. Problem is some snakes like a certain hide and will use it at the cost of overheating or being too cold. Your cage has a nice natural look to it but until you get that little of a snake eating regularly, i'm going to have to say, you need to put him in a smaller more controlled cage. The gal I got Allie from had problems getting her to eat reliably and I didn't say anything but I figured it was from the lack of a "good" setup. Once I got her home and put her in the set up I showed you, she started eating like a horse and growing and is starting to mellow out. Most snakes are fine in large enclosures and I don't buy the "its too large of a cage" thing except if you cant control the set up enough. Like I said, I would check the temps first and foremost because wrong temps and/or insecurity are imo the 2 biggest problems to getting a snake to eat.
Also you said Saturday you got him. So it's been 3 days? Or has it been 14 days for you? If 3 days then that's nothing. If it's 14 days on that small of a baby, I would worry a little. If you got the breeders name and number, I would email him and ask how he was feeding him. If not, you can try a F/T hopper mouse. I don't think I would want to try a live hopper mouse in that set up as it can get away and hurt your snake later. A pinky mouse seems small. I would imagine the snake wouldn't even register the pinky as food as they don't move much. Like I said, I would wait until night, then quietly try and dangle a F/T mouse in front of whatever hide he is in. Then maybe drag it on the ground in front of the hide to perk his interest. If he grabs it, just lightly tug on it to mimic it trying to get away but don't pull on it so hard as to scare the snake. If that fails, just leave it on the floor in front of the snake overnight and pray he eats it when its dark. Some snakes are just shy.
Heck the gal I got Allie from got a couple coastal carpet babies and she cant get them to eat either lol. She's been asking me how I got Allie to eat so well and I told her the same thing, you need to get the cage set up right with temps and security. A cold snake or scared snake is not going to be thinking about food. Sometimes the simplest set ups are the best. I like the naturalistic cages and stuff like Gio does and yours but for me, I found keeping it simple and easy to clean has worked best for me. All my snakes eat like horses and are puppy dog tame except Allie but she is on her way![]()