Jets are the earliest ejected material from a hypervelocity impact event. Jets comprises of projectile and target's surface material and are ejected at velocities higher than escape velocity for Earth. Effects of Hugoniot properties of the projectile and target material on jet initiation are not well understood. We, therefore, developed a mathematical model that incorporated the limitations imposed by Hugoniot properties on jet initiation for hypervelocity impact. This model analysed the effects of changes in Hugoniot properties of the projectile and target on the jet onset time, jet onset velocity and jetting side (projectile or target). The results reveal that (i) jet initiates earlier and at higher velocity if the jetting side has higher value of shock parameter or higher velocity of sound in the material; (ii) jet initiates later and at lower velocity if jetting side has high density; (iii) effect of s-parameter and speed of sound in material is more profound than the effect of density.