Its a question I've asked myself lots of times:
If you are starting a community type of site that's going to get the bulk of its earnings from advertising is it better to start with them in place before you go public, or is it better to build up the user base and then phase in the adverts?
I'm more of the opinion of phasing it in after the users base is established.
phasing in is what Google and Facebook done :)
You thought of advertising your own offers? Eg the lottery, or something else that most people like?
Leave it clean to start with. You want the userbase then you can hit them when they find it useful.
I dunno, LM, at the very least I'd put in some sort of ad space from the git-go even if you just run house ads. You and I have seen instances when the best members revolted and left when the community went commercial.
I'd agree with RC ... include some ad space from the git-go.
Users expect some degree of advertising on a successful site, so long as it isn't intrusive.
But as RC points out, communities *hate* change so better to prepare now for later.
I run a number of forums, and use vbulletin variables to show big ad slots to unregistered visitors, but a single small block for members.
You know. You could "split the difference" so to speak.
Make areas of your site ~look~ like ads, but aren't. They might click to something else (useful research site or whatever, like the food pyramid site: http://www.choosemyplate.gov/, or the notill farm site: http://notill.org/) Get the regulars "used" to seeing the "ad areas" but since they aren't anything but useful stuff, they won't think much of it. Then you can change to real ads later...
And, you could even count the clicks to see what areas of your site are "hot" before you put anything "real" on it.
Or split the difference and find some really nice looking banner ads for products that your community will feel good about, even if they won't buy at all, but which won't put them off. Then rotate in ads that you test against.
Yeah, that's what I like about house ads. You use ad creative that you control 100% to condition the repeat users. Their banner blindness kicks in and then you phase in commercial ads. BTW, I used IAB standard and/or common aff ad formats for the house ads and required advertisers to do the same when they signed up in order to lessen the visual impact of the change.