Hello! A wee bit of history, MySQL sometimes is used on a basis of "grab that web data, if they forgot the time do it anyhow!".
So, you may have to assign a special date/time that will not come up in normal use, like jan, 01 am, 01 mins after the how, 01 secs after the min, and keep on til you fill up all the fields.
Ugly as a mud fence, but that is one way.. now, if all of the times are important, I'll look around for something, this is first thing in the morning, and i'm not too awake yet! ;-)
hope it helps.. btw, I'm both a MySQL and SQL Server dba..