I seldom make a quilt for a customer. When I do, I charge $10 a hr for the piecing. I use an electric clock attached to a power strip with rocker switch and I keep track. This allows me to be accurate when stopping for phone calls, interruptions. You can also do 1 block, time it then multiply instead of keeping track of time, but don't forget you still have to put the blocks together. Figure in an additional 20% of piecing time for assembly (blocks, sashing, corner stones etc). Then I figure in .015/sq in for simple quilting or the rate for whatever type quilting they want. Then add in .10cents per running inch for the binding. You will come up hating the project if you don't. The fact that we do these over time and don't realize our total effort leads us to under charge massively to customers.