If your first post topic doesn't list the date, time, and time zone of your run, expect it to be deleted. I highly recommend the format 'Mon Sep 8 2008 10:10 AM UTC', to be clear to people of all localizations which day you're planning on.
If you're looking to schedule a run in a timeframe rather than at a specific time, give that time frame (e.g. 'Ice Kobolds Rampage - Sep 8-13, 2008 Evening EST'). If you nail down a specific time, you can go back and edit your original post to change the main topic title.
Remember, you can always use the !time SIMTools command in-game to get the time in UTC (but no, there is no requirement to post run times in UTC).