Here's a fairly flexible approach that doesn't assume any particular format of the date on each system, but rather looks at the date format settings on that machine, and gets the month, day and year pieces of the date based on those. They you can build your log date stamp from those pieces.
Let me know if you have any questions.
I'll mention one other item here too. I have a small, freeware utility that I often use for these type of times stamps which works great regardless of the way a system has the date format configured. But it is a small EXE that is needed. Depending on your situation you may want to just stick with pure command line base commands, but wanted to pass it along in case it is useful at some point in the future. It does a great job of getting current date / time, as well as getting dates in the past or future, offset by any number of days you want. Check out DOFF at:
http://www.jfitz.com/dos/index.html#DOFF~bp