How do you drain a garbage disposal?
When I am doing a disposal install (non professional but at least 10 for friends and family) I do a double 90 right away and slope drain down a bit from there.  

After doing the double 90s you don't need that much slope but given you will potentially have food items I would maybe go 1/2" down overall on your straight into the T.



Also BMitch is right.  The AAV I think by code is supposed to be on the surface but that is another question.