When I prepared in LibreCad the dxf of my round PCB I have added there a small cross at circle center. Then importing I placed that cross at 0,0 absolute coordinates and finally deleted it.
I don’t remember if I was able to position it that way at once or I had to use Move Exactly (I was doing it few years ago).
That helped me also to position footprints that were in symmetry regarding the center point (connectors at right and left, round antenna and its connector have coordinates X=0):
