I'll start off by saying I wouldn't necessarily classify this as a trick but John Mueller of Google called it a trick. If your site gets indexed and ranks in Google but you aren't ready for that to happen, you can use the site-removal tool in Search Console to remove it and then cancel that request when you are ready to have it show back up in Google.
John wrote on Twitter "A neat trick is the make the site live & indexable, use the site-removal tool to remove it, and then cancel the removal once you want to be visible in search."
We cache the robots.txt for about a day -- so in the worst case it would take that long to be picked up. A neat trick is the make the site live & indexable, use the site-removal tool to remove it, and then cancel the removal once you want to be visible in search.
— 🍌 John 🍌 (@JohnMu) April 3, 2019
Of course, again, this isn't really a trick but a good to know and have this tool in your toolset. That is of course if Google doesn't kill off that feature in Search Console.
Forum discussion at Twitter.
