Tricky question! What is 6 months before todays date (25 July)? Is it 25 January? If it is, what's 6 months before August 28? 6 months before August 30? Or do you want 182 days and 12 hours before the current time? And 183 days in a leap year? Or at least, between March 1 of a leap year until February 28 in the year after?

Questions, questions, questions.