You cannot. The instrument has no RTC (real time clock) which means it cannot keep track of the real-world date or time. Nor is it able to keep track of time at all while turned off and certainly not while unplugged.

The only way to keep track of the date and time is to place these somewhere in the file names you store/save.

When you see an option that allows you to view a list of data according to the selection you may see the following;
“Default” - the order in which they appear in the Bank
“Name” - the order is alphabetical or reverse alphabetical -tap again to reverse the view of the listing…
“Date” - the order in which you created the data or reverse order

It does not literally mean the actual calendar date. The cataloging includes in which order new data was generated.