Hi Vish, 

I believe you can user our out of the box report to do this. This would be the user performance report which can will allow you to see what actions have been undertaken by specific user as well as the date and time taken to open and complete the action.

For versions 4.7 and below:

https://help.k2.com/onlinehelp/k2blackpearl/userguide/4.7/default.htm#5.Reports/WS_User_Performance_Report.htm%3FTocPath%3DReport%7CK2%2520Workspace%7CStandard%2520Reports%7C_____5

For versions K2 Five and upwards: 

https://help.k2.com/onlinehelp/k2five/userguide/5.1/default.htm#Create/K2Designer/Controls/UserPerformanceGrid/UserPerformanceGrid.htm

This goes more into detail as to what chart controls can be used and if needed you can see other configurations on the left hand side. 

Kind regards, 

Percy