The files that FCP X renames with time and date, select one or several or all in the LIST view of the Event Browser. Go to the menus Modify > Apply Custom Name > Original Name From Camera.
You can also right-click on any heading of the Event Browser in LIST mode, and choose which headers to turn on and off. There is one for Date Imported, which includes the time it was imported, also. Click on that (or any) column header to sort by it, and click a second time to change the sort order to ascending or descending.
You can also go to the Event Library/Event configuration menu, gear icon below them, and set up how you want the clips to be sorted and shown in each. The top section is for arranging the Library. The lower section is for the Browser. Go to Group Clips By and select Date Imported. Then back to that menu to set it up as Ascending or Descending.