Apart from John Georgiades kicking 8 goals on debut for us against Carlton at Princes Park in the opening round of 1989, I immediately thought of Ben Sexton kicking a bag on debut (not sure of he kicked 5 or 6 goals) against the Brisbane Bears at the kennel in 1991.
Thought you might have also been talking about Ross Christensen but he kicked a bag in his 2nd game (against Hawthorn at the kennel in 1982). Was Bluey Hampshire's first win as coach after taking over from Royce Hart a couple of weeks earlier. We came from a mile back at 3/4 time to get up.