Help setting stroke placement to surface

I can’t seem to solve this myself. I’m trying to have the surface placement(draw_mode) set to SURFACE for the active greasepencil after session starts or if possible, before.

def modal(self,context,event):
        self.count +=1
        actObj = bpy.context.active_object
        if self.count == 1:
   = False

            bpy.ops.gpencil.draw('INVOKE_DEFAULT',mode ="DRAW",)
   = 'SURFACE'

        if event.type in {'RET', 'NUMPAD_ENTER'}:
            #do something

does anyone understand what I mean?