LA -- It depends on lots of variables, plus what you mean by "hides them in the grass while she feeds." As soon as they're able to wobble around, she moves them from the birth spot. She'll continue moving them from time to time to keep the scent down. Only when they're able to outrun most predators will you start seeing them in the open with mom. I was born and raised and came to hunting in OK, back when only the Cookson Hills had deer. Today, here in CO, with mule deer (not much different than whiteys in this regard), we keep our dogs under close control for a month after June 15, which is the peak of fawning. Thanks for looking after your future deer population by not mowing. Along with market hunting, one of the most devastating practices to American wildlife in the early 1900s was "clean" farming, where they plowed and cut as close to fencelines as possible, using every foot for ag and leaving no hiding cover for wildlife. Studies of predation show that it's only a real problem for newborns where hiding cover is insufficient, for whatever reason (drought, overgrazing, recent fire, clean farming ...). Use a telephoto, and good luck. Dave