Another possibility?
I've found two dates when Jupiter conjuncted Saturn, but no date where Mars, Jupiter and Saturn were all conjunct -- a super star in terms of drawing the attention of astrologers of that date. However, there is a date where some interesting things are happening.
Feb. 5, 5 BCE, at 7:20 PM, Bethleham. In this chart we find:
1) The Sun has set, bringing night to the sky. On the western horizon lies Mars at 1 Pisces, Saturn at 19 Pisces, Jupiter at 25 Pisces. All of this in one sign, all of this following the prior Jupiter-Saturn actual conjunctions.
2) The Moon rising at 2-32 Virgo above the ASC angle at 6 Virgo. Pluto, although unknown at that time, at 11 Virgo.
3) Mercury and Venus would be well below the horizon and not visible except in the mornings. Only Mars, Jupiter and Saturn would be visible at sun set in the west with Moon rising in the East, an important time of the day.
In prior Jupiter-Saturn conjunctions, Mars was not anywhere near them. So, only those two planets (as a conjunction) could be used as the major sky significator. Mars wasn't a player.
IN SUMMARY, it appears that the Fall period, around Sept 6th or Nov 15th of 6 BCE are possibilities IF the bright star was indeed the Jupiter-Saturn conjunction. It appears that the following spring around Feb. 5th 5BCE is the only period where the three planets Mars-Jupiter-Saturn could be considered by the ancients as being in a sign conjunction and also visible following sunset when viewing was most optimal -- plus the Moon was rising in the east. The horizon played a big role in marking important dates as fixed stars and planets appeared and disappeared.
Dave.