if you mean the time of QlikView load you can use the function
Returns a timestamp for when the script last finished reexecuting.
if you mean the last time a record in a db table was updated/inserted, you need an ad hoc field in the db table
In script, ReloadTime() returns the end time of the previous reload
For start time of the script you can use a variable at the beginning of the script
LET startofthescript = now(1); // 1 Time at function call