7 October 1915
If that is the date on the bottom left of the MIC then it is the date he landed in a "war zone" It should also say "France" or whatever, or if not give a number that you can translate to the war zone.
If you go to Long Long Trail and look up the Regt, then see what battalion landed in France that day, it is usually a good pointer that that is his battalion (but obviously not 100%)
The dates are put on if the man qualifies for 1914 or 1915 Star