There is an organization in Denver that markets the Art District. I'll likely join them, and therefore be included in their marketing. Otherwise, the location I am working on gets a lot of traffic, and the sign in front will be the major announcement.
Our web site will also have an announcement -- it is currently just my wife's blog, but is connected to her etsy shop, so we do have a small following.
If there is interest, I can post on HN as well. I wasn't sure if the community here would have a strong interest in my project or not...
Finally, simply word of mouth - as my day job will pay the mortgage on the property, I don't actually need to profit, so I can just work with my friends on the first few shows, and get the world out gradually.
In terms of timing, I am hoping for August. Once we actually move in (hopefully on the 31st), we need to physically prepare the location (needs new floors, doors, drywall, lights, things like that). So there is quite a bit of work to do yet.