According to the script Superman met the EPRAD scientist in the evening and from then on it was 99 hours and 54 minutes until impact, so it would have hit sometime during the night, probably around midnight, assuming Clark met the EPRAD guy at around 7 p.m. or so. As for the day, the original air date of the episode was 1/2/94, so sometime in January? I think you can be fairly flexible here and make up whatever date you want.
Thanks in advance.