Frozen urine is usually good for at least one year. In the fridge maybe 5 days at the most. Put it in the fridge it should be thawed in a day or so. Get one of those 4 hour energy 2 oz bottles from any convenience store to use for the sub. Put the urine in the container and fill it. Put in the microwave for 8 seconds and then jock it in your taint. It should be at an acceptable temp range for several hours, at least 3-4.
Don't be nervous, just think of it as going in an enclosed room and pouring some fluid in a container and that's it. It really is a joke to do if your not under a court order or probation and have to be observed. Follow the substitution sticky.