If the new entries are at the bottom of the list, then this formula for a date time formula field will parse out the date/time into a date/ time field type. You just need to edit the first line to put in your own [field name].
var text DateAndTime = Left(Right([append only with date /time],"["),18);
var date TheDate = ToDate(Left($DateAndTime," "));
var timeofday TheTime = ToTimeOfDay(NotLeft($DateAndTime,9));
ToTimestamp ($TheDate, $TheTime)
------------------------------
Mark Shnier (YQC)
Quick Base Solution Provider
Your Quick Base Coach
http://QuickBaseCoach.commark.shnier@gmail.com
------------------------------