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Dates are ripe when they start turning brown. They'll also be slightly soft to the touch. Once you start seeing these changes, it's time to pick the ripe fruit. Very immature dates will be green. They'll turn pinkish or orange as they are starting to get riper. Dates will ripen off the tree, so if your dates are being eaten by birds, you may want to harvest them early. You can also put netted bags over the fruit to keep the birds from eating them. As dates ripen, they also start to wrinkle. They almost look like a large raisin. When checking for ripe dates, look for wrinkles, as well. Dates ripen at different times. To maximize how many dates you get off the tree, you need to check it at least once a week for ripe dates. Watch for the pink-orange fruit, as they will ripen in about a week.
Look for soft, brown fruit. Check for wrinkles. Look for ripe dates throughout the season.