No, it's a bad idea.
Why would you want to adopt the kitten now if you cannot takle care of it now? Why not wait the few days until you're back?
It's not nice not to clean the litter box for 3 days. Cats are very clean animals and this might actually cause the kitten to not use the litter box, because it's too dirty.
You don't know if the kitten will eat your food. Your question is missing the information about how old the kitten is, so I'm not sure what kind of food is appropriate. If you're not there to take care of it, you won't be able to intervene if the kitten refuses to eat your food.
Besides, you have no idea what the kitten might do, where it might go or climp or jump. Cats that are locked in an unknown room will usually try to escape and they will try all the ways to escape they can possibly find. If the kitten hurts itself trying to escape or gets stuck, you won't be able to help it. In the worst case you might come home and find it dead.
Where I live it's common for windows to tilt, so they are opened just a gap at the top but are closed at the bottom. Many cats have actually died because they tried to escape through the gap and got caught in the window. They either die by strangulation or they struggle and slide deeper into the narrowing gap, which causes internal injuries and bleeding.
Other people report that their cats drowned in the toilet bowl. I assume the cat wanted to drink from the water in the toilet and slid into it. Again other people report that their cat got stuck in a place that seemed to be too small for a cat to ever get in there. There are also stories about cats sticking their heads into things like jars or cans and then they cannot get their head out. If this happens to your kitten and there's no-one there to get it out, it cannot eat or drink.
There are so many possibilities for a frieghtened kitten to get into trouble on its own that I wouldn't leave it alone until it got used to this new situation.