Need suggestions on how best to run a 40k Campaign 1 Day Event?

[Proiteus]

We recently did a poll on my club's facebook page for Saturday events for next year and we've had a lot of votes for a 40k Narrative Campaign.
I've done Narrative campaign before with a map for players to gain terrtory for victories and allowing players to design their own missions based on narrative, one of the best ones from the last campaign was a train robbery. But doing it all in a day is new to me, I've also sadly never been to a campaign event at Warhammer World.

So what advice and suggestions can you offer on smoothly running a 40k campaign as a 1 day event? If you've been to a campaign event, how was it organised and ran?

Obviously I want two or three parties for players to join and I was thinking of making the first game a small 500pt one as everyone sends out their scouting forces. But I'd like some help figuring out what do for the rest?

[Charon]

Tree Campagin tournament style.

You start with lots of 1v1 games (assign every table a different mission) and end it with a big table (2 sides) where everyone contributes with a few units and adds boni to his side depending on the achievements ont the tables before.
Should roughly fit in a day and nobody is left out even if the group is bigger.
Quick and dirty.