You have Username but unsure what is their computer name where they logged into to track it(this all happens if and only if sccm client is healthy else you see old information).
This report gives you all the machines name with your supplied user names if you have bulk users to know all .
Create report with below SQL code and Run
Other SCCM reports based on last logged on user names http://eskonr.com/2011/03/sccm-report-for-computers-with-last-logged-on-user-from-collection/
GS.ResourceID = SYS.ResourceID
AND WS.ResourceID = GS.ResourceID
AND OS.ResourceID = GS.ResourceID
AND Datediff(dd,WS.LastHWScan,getdate()) > -1 and
GS.username0 in ('eskonr\eswar','eskonr\koneti','eskonr\test','eskonr\test1')
order by UserName0
You can add multiple users by separating comma(,) from above In command.