Each animal is different and situations vary on each possible draw. My rule of thumb is to carefully observe the animals movements. Watch what their head is doing, regarding movement. Like humans their bodies follows what the head is telling them to do. Watch for an upturned head with nose seeking it's possible dangers. Watch their ears closely. Upright ears tend to tend to exhibit a cautionary pose, straight back ears mean they are ready to bolt, downturned ears are a sign of relaxation. When a head drops this also is a relaxed pose. Head turns with upright ears, another alert, sensing mode. While I observe I always wait for a relaxed head mode before I draw. It's just me but I want a relaxed unsuspecting animal to receive my arrow. I have just learned over the years that too many animals are missed completley or worse maimed by errant shots. Most of us spend many hours looking for our game. I urge all to be patient, for that ethical shot you will be so proud to have accomplished. Those few extra moments or even minutes will save you many a nighmare over missed, wounding shots and the despair of lost game. We do owe it to them and ourselves.