Going from various problems I saw with systems with smaller time wraps, setting a time after wrap occurs misses most of the problems which wall occur. Many systems will work fine with either 'negative' or 'smaller dates' but crash, burn, etc when running when the counter wraps around. I would suggest setting the test date to -N minutes before wrap over to run a first set of tests, and then N minutes after the wrap to run a second set of tests. This would hopefully catch programs which are worse off.