How I can to mill the face of the wood before the machine will start to carve??
Well to be honest, you could write the Gcode to make the router move in a back and forth pattern and then index over a certain amount and repeat. I did this to mill down my table. You could also draw the lines to do this in a cad program as a DXF.
You could do it in Easel as well by just drawing a square the same size as the material and and “clear out the whole pocket” to a certain depth. In the advanced portion you can change the stepover and bit size as well as the depth of cut. In cut settings you can choose the manner in which the cutter moves, x axis raster or offset.