I would suggest not using a hoop smaller than regulation. Basketball skill is built through repetition. If the repititions that you're taking are unrealistic then you won't be able to perform under realistic circumstances.
If possible i would suggest returning the hoop because there WILL RUIN YOUR GAME. By praticing on a 8 feet court you will ruin your game because your mucsle memory will be used to 8 feets not 10 feet. Just like when you learn how to shoot the basketball your form won't change unless you make it change since your mucsle memory is used to how you first started.... If u play an instrument or u type the only way u get better is by mucsle memory to type fast of course u have to pratice so your mucsle memories remember where to go to rather than using your mind memory so even if you don't return it all i can say that court is go for if you don't wanna ruin your game is to dunk so you can get the feel of it.