I have to agree with Clint on this... don't overthink it. You only need a compass or a map to give you an idea where North is. If you have the antenna hand-held or on a small tripod, you will use it more with your ears than eyes, like a metal detector, but pointed at the sky --- sweep back and forth, and also rotate the beam around the boom axis for polarization changes, and listen for maximum signal/minimum noise. You will be continually be updating this during the pass... use your ears.

I print out the AOS and LOS (acquisition and loss of signal) bearings, and max elevation values to give me approx. start and stop location, and to make sure my location accounts for the tree line and any buildings/obstacles. But I am still sweeping back and forth with the Arrow as the bird pops up over the horizon, and then optimize it when I hear the bird.

Spend the money on a good accurate watch and a voice/tape recorder. :-)

Bill W1PA