[whpalmer4]

It is recorded automatically, but there isn't a column to show it. If you select the item and bring up the Inspector, you'll see a Date Added field (and a Date Changed field, as well). You can also group and sort by these dates. So, if you add a bunch of stuff today and want to mark it all as having the same start date, you could bring up an All items view, switch to Context mode, change the grouping selector in the view bar to Group by Added, and the items added today would be in the first group. Select them all, bring up the Inspector and set the start date for the whole lot at once.