Your friend was correct. 8 is the number. Anyone who ever needs this information is welcome to e-mail us at email@example.com or post here if you don’t mind it being public.
To figure it out, take your best two of four differentials from your last years tournament (that number to the right of each score in your ghin) and average them. I only mention this because learning about differentials is key to understanding the handicap system as a whole!