DrAsus

personally if this is the first trip I start @ 25 yards and get the scope lined up so that you a dead on left and right and maybe a 1" or less high @100

Then normally I go to 50 and repeat the process then a 100

I can not remember what projectile you are shooting but if you sight in @ 100 yds 2/3 inches high and dead on left and right chances are really very good that you will be very darn close at 150 - but only shooting that range will tell you for sure