According to the report Mian Shehbaz Sharif has received the summon today (Tuesday) and asked to appear before the JIT with all relevant records.
But the report did not mention the date that when the CM Punjab will appear before the JIT.
Article source: http://www.suchtv.pk/pakistan/general/item/55317-panama-case-jit-summons-cm-punjab-shahbaz-sharif.html