With Google’s new mobile ranking signal set to roll out in less than a month, there are plenty of questions surrounding just how long the roll out will be.

SEOs are accustom to seeing updated algorithms roll out over several days – or even weeks – particularly large scale ones.  But with the mobile ranking signal, it wasn’t quite as clear cut as with some previous updates.  And sometimes we see changes go out within the US only, while others we have seen hit other geographic regions first.

But this particular ranking signal is a bit different than usual algorithm updates, and most closely resembles when HTTPS received a boost (albiet a slight one) in ranking signals.  This new mobile ranking signal will only affect searches done on mobile devices, and it seems the only influencing factor in this signal is simply whether a page on a website passes Google’s mobile friendly test.

We now know just how long the roll out will take.  According to Mary on the Webmaster Team at Google, in a mobile friendly ranking change hangout, stated that the roll out will take several days or a week to completely roll out.

We’re expecting to roll out on April 21st.  We don’t have like a set time period because its going to take a few days to roll out, like maybe a week or so.

Gary Illyes stressed at SMX West last month that April 21st would be very important, but that if all pages aren’t done at that time, as soon as Google crawls a page that has recently been made mobile-friendly, it should  get the ranking boost.  However, there could be a week or so delay if you have pages that weren’t ready on April 21st, as sometimes when a new algorithm or signal is rolled out, it doesn’t take up-to-the-minute data into account while a roll out is ongoing.