If you are moving hosting companies and want to avoid any problems with Google rankings here’s a few tips:
1) If possible don’t move your domain name to the new host until the site is up and running on the new host.
2) If that’s not possible then John Mueller’s Twitter Tip of the day: “If you have a generic “your site will be hosted here soon” page, use “noindex” or 503 result code, thanks!” could be the answer.
A site owner recently posted in the Google Webmasters Help Forum about a loss of rankings after moving hosts. Google’s JohnMu had this to say:
“It looks like your site might have shown a generic server start page for a while (a “This is the default … server page. (…)” page). When this happens over a few crawls, it can confuse Googlebot enough to cause problems with the indexing of your pages. At the moment it appears that this is no longer happening, so I imagine it’ll just resolve itself automatically over time.“
Combined with John’s Twitter post he’s given us the answer, add the relevant status code or noindex if possible and all will be sorted.