A couple months ago we reported Google was testing future open dates within Google Maps listings and Google My Business. Well, this weekend, Google officially announced it in the Google My Business Help forums. Allyson Wright, Community Manager, Google My Business, said "We're excited to announce that Google My Business now supports businesses that haven't yet opened to the public!"
Allyson said:
Soon-to-open businesses can create a Google My Business listing before they open. This helps them build their online presence and be ready for business on Day 1. Businesses can set a future opening date, engage with customers, and announce when and where they'll be open for business.Verified businesses with a future opening date will begin to appear on Google 90 days before the opening date.
When you create a new business listing in Google My Business, select the verify later option and then you will be able to select the future opening date. Again, when prompted to choose a verification option, select More options and then, under "Verify later," click Later. From the menu, click Info, you will fin the "Opening date" section and click the Pencil icon, then enter your opening date and click Apply.
For more details, see this help document.
Here is a screen shot from a couple months ago:
Forum discussion at Google My Business Help.