the best time to call in grays is at night but if thats not possible then your only chance is that time period between first light and sunrise(about 30 minutes or so)after that they will hole up for the day.very unresponsive to calling during daylight hours.and then again just before dark.reds are also best hunted at night but in the winter time will mill around for a few hours after first light and hour or so before dark.during times of extreme cold temps they can be had all day.your call box volume for reds should be kept at #3 or lower on the dial.reds will and do spook from excesive volume.i have had red fox come in after 30 minutes or longer but most times they will show in ten to fifteen minutes.i once had a three legged red take 40 minutes to come to with in shotgun range.gray fox and coyote you can use more volume but still would not use more then #5 on the dial.they to will spook to excesive volume,you just can get away with a little more then with reds.these volume settings are based on dead calm or near calm days.windy conditions with hilly terrain will require more volume.the time need to stay on stand is 30 minutes max.grays will generaly run you over in less then 5 minutes and reds can take 15 minutes or so.you can stay longer and try for the staglers but your time will be better spent and more productive moving after 20 to 30 minutes.if coyotes are your main target then stay the full 30 minutes.grays will most times come busting in with out any regard to wind direction,reds on the other hand are more like coyotes.they will cirlce to the down wind side to size up the situation.for me personaly i have found mornings to be more productive for fox and coyote.one finale note,when approching your stand sites be in stealth mode.no talking and make as little noise as possible and never allow yourself to be skylined if you can help it.make sure your camo works with the area and wear gloves and face mask.if theres snow on the ground then snow camo should be worn.a predators very survival depends on there ability to use there eyes,nose and ears,if you are careless on your approch and while on stand you don't stand a chance.