I've read all the guides and always get the same result. Initial rank loss, some pages recover and some don't. Some http remains 6 months later anyway which tells me that the sites link profile is still not up to date for a long long time.
- If you apply a rel canonical tag pointing at the https version you are wasting your time if you also 301 redirect visitors from http to https. Why? Because google can't see your canonical on the http version anymore, they don't get he memo, they get redirected too.
- By leaving both versions active for about 10 days the monster share of URLs in serps will be https. Via redirection it's barely getting started.
- Search console fills up with https NOT selected, we think the http version is better, when you redirect from http to https.
I agree with immediately updating all internal links, and external incoming links if you have access, to point to https but those 301 redirects slow down the show quite a bit compared to letting Google see both versions with the new canonical.
I agree that, eventually, a 301 should be made sitewide to https, but right away? It doesn't seem like a good idea anymore until Google has had a good sniff of both URLs and they can't do that if you 301, they never see the new canonical on the page they know.
Has anyone tested this? I'm migrating another site and this time leaving the redirects off until I see serps have propagated. "site:example.com inurl:https" shows how many pages google has switched to https in serps.