I agree with @code delta that your loop is set up correctly. However, you may have a bit of a problem with the lockout for the Sharks vs Dragons match. It will be very close to locking out as the Storm vs Knights match finishes.
You could watch Welch for 60-65 minutes of his match and do a bit of a guestimate as to what you think he will get in 80 minutes. If you think he scores poorly then make the JMK to Leilua switch before the match ends (before 7.20 pm AEDT)