Ms. Grace, what we did was as the top (or backing, did both the same) was being rolled we put our hand around the take up rail (like you hold a glass) and smoothed the fabric from the center out in each direction. Be sure to just smooth, and not stretch. Roll a little more, smooth a little more, and keep an eye on the ends to make sure they stay even.
I know the frames say no baste, but both the long arm quilters I know tack or stitch around all edges of the quilt before they start stitching.
You can tie off and start again if you need to; I was told many people do that when they are learning to long arm because, let's face it - we never practiced doing things backwards or upside down! Sometimes the quilt or the planned quilting actually requires it.
The more I work on one, the more I admire people that do it well - it certainly isn't easy!