Hopefully you will!!
It all really depends on the character rotation and where in the building your seated. You could be at a table in a section that was just cleared, that the characters just went through. Thus, you're last on the list of the set, and it could take a while.
Or you could be sat and see all the characters basically right away, and then grab food and be done!
It's all really chance. My advise: ask for the bill right at the start, if you settle it then, you don't have to wait for the server to come around again to grab it, I find they kind of disappear at buffet meals a lot.
Also remember that you can get Pooh and Tigger elsewhere in the MK, so if you skip them it's not the end of the world. You can also find them in AK.
Eeyore and Piglet you can't!
Have a great trip!