posted September 25, 2011 12:48 PM            

Tr Sun (1-2 days)
Tr Moon (2-4 hours)
Tr ASC, Tr MC and Tr Vertex (approximately 10 minutes; depends on the ASC sign actually)

EDIT:
to what in the natal?
To Venus and Node would be about love or creative connections.
Significant events will also trigger personal points and planets in your chart (Sun, Moon, ASC, MC, Vertex and those tied to the personal points).

These are the exact triggers neetded to narrow it down to the day and hour; of course Mars or Node may be important, too, but they operate over a longer timeframe, so you need triggers for the exact moment.

Also check the planets that are in exact dynamic aspects with Sun, Moon, ASC, MC and Vertex.