Pulse number one should happen the same day as your event, or the very next day at the latest. This should be something that says, "We loved seeing you there," or "If you weren't there, this is what you missed." And you want to give them something of value – be it a video, a cool quote, or the playlist from the DJ.
But this is important: in this first follow-up, do not ask for anything. This is about giving, trying to derive value, and showing continued gifts through your outreach.