boyfriend is a spoilt brat.

My boyfriend is completely petty and childish at times and I cant stand it. I went to Florida and the prices are generally cheaper there so I asked him if he would like me to buy anything specific for him. He sent me a pic of a pair of sneakers.  They didn't have it at the store so I called him on FT and showed him the other options for me to purchase. He told me which to buy for him and It was expensive. I spent the most money on him on my trip and I told him although he knows what I bought it is his  gift for his birthday in October so he will get it then. 
Since I've gotten back hes been demanding that I give it to him now although I told him I purchased it as his bday gift so he would have to wait till then. 
Now hes behaving like a spoilt bitch and telling me I shouldn't have shown it to him when I purchased it if he can't get it now (although I told him he wasn't getting it till October before I purchased it) and how I wouldn't like it if he did that to me. 
Honestly am I wrong for buying his bday gift in advance?? I seriously regret even purchasing that gift now. The way he's behaving is so unnecessary am I right?