If the symptoms only appeared after the clutch replacement, the most likely cause of the jerking upon take off would be poor friction surface preparation prior to clutch reassembly. The new pressure plate was coated with oil based corossion inhibitor and was not cleaned with a non petroleum based cleaner such as brake parts cleaner or carb cleaner. Or the flywheel surface had oil residue, or the "mechanic's" hands were too dirty and he touched the friction surfaces with them. Your frictions may be slipping from contaminants.