If you are going to stretch before jogging, you must warm up first. Never stretch cold muscles, you are likely to cause a tear.
Warm up first by jogging on the spot, stepping up and down on a low bench or stool and also do some mobilisation exercises, like arm bends, shoulder shrugs and knee bends. You can then stretch.
A warm up can also consist of just walking at a moderate pace and then to a brisk pace, for around 5-10 minutes, before breaking into a jog.