You will be able to get a birthday button when you check in, and he can wear it all week if he likes and will get lots of birthday wishes! You can also note it on your ADRs and he may get a special dessert, card or confetti on the table - some places do, some don't - my daughter had a lot of fun little surprises last trip for her bday.
Also, if you do get an early ADR, you can enjoy the empty main st. for castle pics and get photopass to take magic shot w/ Tink, and if you order prints/CD you can put in birthday borders/wording I believe. (don't know if you've done this before) Plus you'll have a head start on the park when you're done. Enjoy!
cassie58
11/08-ASMo & Timeshare
8/09-CSR
11/11-CSR