As you can see, there are lots of variables to answering the how long is hamburger meat good for question. Raw hamburger meat (ground beef) is much more perishable than other cuts of beef and will keep in the refrigerator for only 1 to 2 days. Cooked hamburger meat will keep 3 to 4 days in the refrigerator.
Re: Poured side walk/steps, how long to leave forms? I strip the forms 24 hours later, but am careful not to damage the new concrete. It will still be very soft and with crumble if you put too much force on the edges. Usually concrete will harden withing 30 days to the point where it is considered cured.
Concrete hardens to 600PSI (Minimum) after 24 hours. This means that 5 three grown men could all stand on a pogo stick (if that were possible) who's base covers 1 square inch without harming the concrete. You walking with shoes on exert about 10 PSI, well below anything that could damage the new pour.