First birthday question?

My sons birthday isn't for 4 more months but I'm concerned about how far in advance we should book.were aiming for this really neat pizza place with a big play room for te toddlers and lots of people have parties there so I'm not sure how I should go about booking us a place...well have 60 plus people so well need quite a bit of space. How Should we go about this any suggestions? Btw not that it matters but the theme is Dino.:p