Three days: Slightly brown and bruised across the surface, texture was very soft and kind of slimy from the juice. One week: Surface of the avocado was brown and extremely soft. The avocado surface had changed to a slimy, stringy texture. Though it didn't smell rancid or rotten because of the lemon juice was still overpowering, the color and consistency indicated heavy oxidation and that the avocado was no longer edible. Using lemon juice may be a good short-term storage solution, but not for more than 3 days in the refrigerator. The avocado will still have a slimier texture and take on the flavor of the lemon; but I am personally okay with that, especially if I plan on using it for guacamole.