Need help on the details of mounting an octagon box that will be embedded in a brick wall. It's new construction, a block foundation wall with a brick face. The block wall is up and I need to locate a box for a light fixture that will be on the wall beside the garage door. My thought is to drill a hole in the block where I want the box to be, rough in a length of nm from the switchbox through the block, clamp the nm through the side of the box and let it hang, leaving it for the masons to locate so that it's easier for them. Does this sound right?
If so, how is the box captured by the brick?
Are there boxes with brackets for this purpose? Or should I attach the box to the block using screws and anchors and let the masons work around it?
Most of my work has been in industry and old residential work and I have not come across this until now.

Thanks, donles