An unloading plunger having an internal chamber to hold compressed gas and a timer-operated valve to release the compressed gas through a gas jetting port as a jetting force for ascent of the unloading plunger in a wellbore to unload liquid from a well. The ascending of the unloading plunger may be via a combined motive force of wellbore pressure provided by formation pressure plus the jetting force provided by ejecting the compressed gas from the unloading plunger.