Note that the Machine -> Work Area and Material Type X/Y/Z dimensions are for visualizing only. They can be anything but nothing here will affect alignment issues. (disregarding Z in this instance)
The only thing that matter is the Easel home position (work/material zero) match the design zero, so they are indeed aligned.
With a premade blank I would find its center, and jog my bit centered over it and use that as Home position (work/material zero)
The design need to be centered aswell, see image for an example:
(Everything will be carved, not only what is visible in the right preview)