Trying my walking foot...what should I stitches be set at?
 

What should the spacing be on my stitches when I try to quilt with my walking foot?

You can set it where you usually do and it should work fine. I set my stitch length to about 3.0 when quilting with my walking foot, just because I think the longer stitch looks better. But when sewing my binding on with the walking foot, I set it at the usual length of 2.2 or so.

I set my machine @ 3.5. Just my personal preference!!!!

Depends on what you are trying to stitch I have used anywhere from 3-3.5. I used the higher for minkee