It is senseless to not give the date of the event. If you make the target a six month period, it is an attempt to test the impossible. Many things might happen in six months. It would take weeks to scan a six month period, and then pick one in many contacts in that time.
There is no reason to hide the exact date of the event. How could the astrologer cheat? If all he has is the chart and the date of the event, then that is a real test. If he has a six month period to scan, it is a pointless test of astrology. It is rigged to fail, and it is a monumental waste of lots of time without a paycheck. No, no, no.