oh lord my husband wanted that too when we got married. Our wedding was on 8th, walima on 10th and his bday on 12th. He initially wanted walima to be on his bday I said NO. I wanted these two days to be seperate so that I could cherish more days with him. Bday on Walima day would've ruined everything. With going to get ready from coming home exhausted, just didn't want that. I wanted a whole day of me and him together with going out to eat ... celebrating with his family and friends.. We did that. I am glad I changed it.
But to answer your question, I think it will be ideal for you to celebrate his bday the next day. Like book a nice place for dinner and have that whole day of just you and him. Walima day bday won't be fun.