How much extra backing do you need (usually 3-4 inches all the way around)
If you have any ideas about what you would like, let her know that, as well as what you don't like. For example, if you don't like feathers, let her know!!
Let her know your budget for this quilt, and any others you do. You may not want to spend as much per square inch on a baby quilt as you would a wedding quilt.
If you are interested, see if she attaches binding on her LA. This is something that I can do while the quilt is on the LA and my customers don't have to wrestle that quilt with their home machine.
If she trims the quilt - how close do you want it trimmed? Some people don't want them trimmed, some want it trimmed right up to the edge of the quilt, others (like me!) like it trimmed 1/4" away from the edge so the bindings are full and the edge of the binding meets right up to the binding seam on the back.
Does she have pets in her studio. Do you care? And let her know if you sew around your pets - some quilters have allergies, too!
Some quilter's have a backlog (the good ones usually do!). Ask if you can be put on her list, then get the quilt top to her a couple of weeks before your time.
HTH!!