When creating surveys, campaigns etc, it can be confusing for most people outside the US when the date is in US format ie mm/dd/yyyy. I think it would be very professional for your non-US customers, of which I imagine you have many, that you change the format according to their location. UK customers, and most of Europe is accustomed to the dd/mm/yyyy format, and this is particularly important around the middle months of the year where a date of 6/5/15 is 5th June in the US but is 6th May in most non-US countries.