Hi David,
Yes, you can set a vertex to be the anchor of your polygon:
Select your polygon, then, on the 'Edit' tab, click 'Move' within the 'Tools' section. This will display a yellow dot over the centroid of your polygon. Hover your mouse over the dot, then while holding the Control key, click-and-drag the yellow dot to the vertex you wish to set as your starting point (make sure your snapping is set). You can now shift your polygon while maintaining its shape, and position it using this vertex as the anchor point.
Regards,
Greg
