If you want to position the probe after homing Z
G1 S1 X-269 Y-261 F1800 ; move quickly to X and Y axis endstops and stop there (first pass)
G1 X5 Y5 F6000 ; go back a few mm
G1 S1 X-269 Y-261 F360 ; move slowly to X and Y axis endstops once more (second pass)
G90 ; absolute positioning
G1 X51 Y20 F6000 ; go to first bed probe point and home Z
G30 ; home Z by probing the bed
Add a G1 X Y move after the G30 that puts the print head where you want it.
Also, the G1 X Y move BEFORE the G30 should be changed so that it places your probe at the center of the bed. Maybe I totally misunderstood you at first and that's actually what you were referring to?