Don't emit T0 at the beginning of the file, so that it's generated automatically just right before starting the print

lib/Slic3r/Print.pm

@@ -648,7 +648,6 @@ sub write_gcode {
     );
     my $min_print_speed = 60 * $Slic3r::Config->min_print_speed;
     my $dec = $gcodegen->dec;
-    print $fh $gcodegen->set_extruder($self->extruders->[0]);
     print $fh $gcodegen->set_fan(0, 1) if $Slic3r::Config->cooling && $Slic3r::Config->disable_fan_first_layers;
     
     # write start commands to file