On my CNC mill, I have the ability to use the controller (actually the software) to calculate the center of a given space. I think this could be done in LightBurn too.
Move the laser head to the left of your engraving area and “mark” it. Move to the right of the engraving area and mark that. The software calculates the midpoint and puts the midpoint of the file to be engraved there (in X). Do the same for Y if you want to center vertically. You could do X or Y or both.
This would make placing an engraving exactly where you want it very easy and would not need to account for the lead in (as you do if just using the frame function).