First, welcome to BB and bunny slavehood! Feel free to head over to our welcome section to introduce yourself and your bun!
Bunnies can go away from their moms at 8 weeks minimum, so I hope your bun is at least 8 weeks. The first thing I would recommend is finding a bun-savvy vet who can give you pointers and assistance about age, breed, diet, any health issues (especially with a pet store bun as sometimes they pick things up from other creatures at the store), and “fixing” your bun when they come of age.
If you just got the new bun then he is going to be very jittery at first: new place, new home, new people. It’s going to take some time for him to adjust. Let him explore a bun safe room at his own pace and time. Let him decide when to come up to you and when to give you affection. This will build trust between you and your bun since he won’t be worried about you swooping down on him at any second for cuddles. Bunnies in general hate to be picked up and held (they are prey animals and you look a lot like something that wants to eat him) so don’t think of it as your bun not being affectionate. I’ve had my bun for over a year now and she only tolerates being held in a very small doses and only if absolutely necessary.
Do you know about bunny diets? Since your bun is so young, make sure they’ve got a good quality hay (timothy is the best!) This should always be avaliable and it should be fresh and pleasant smelling. Also, at a young age buns can have unlimited pellets, but you want to make sure the bag only contains pellets. Avoid bags of pellets with “other” things in them: like nuts, corn, ect. These are actually really bad for your bunny. Since you think your bun is so young, I’d avoid veggies until you find out just how old he is. Bun can start on fresh greens at 12 weeks, but go slowly. One veggie kind at a time, and no more than 1/2 cup to start and then you can gradually increase. You can find a list of safe veggies from Binky Bunny at the top of your screen under “Bunny Info” I recommend cilantro.
If you have any other questions, feel free to post them here at the forums. Everyone here is really helpful!