When should hreflang be deployed in this situation; now or later ?

[Dan-Lawrence]

HiI have a question in regard to point 1 in Gianluca Fiorelli first comment on Aleyda Solis old but great international targeting article in regard to hreflang: https://moz.com/blog/using-the-correct-hreflang-tag-a-new-generator-toolit would obvs be amazing if either Gianlucca or Aleyda can answer but if anyone else feels they can do so confidently then that would be great too :)I'm advising someone in similar situation as that (their main brand is USA based on a .com showing up in UK searches too) and they have launched .co.uk sites (without any seo) to target UK brand searches, so obviously the .com is still dominating UK serps for brand, and the .co.uk is ranking on page 4 on average for a brand search.**BUT **before I tell them to roll out hreflang shouldn't they build up some authority etc first for their new country specific (.co.uk) site ? since they are very new and have no authority or even basic SEO and don't rank higher than page 4 for brand searches (the .com is in no1 in both usa and uk).I know hreflang needs to be used correctly here but im not sure when it should be, now or later (after authority has built up for the new uk focused sites) ?In other words I take it deploying the hreflang correctly wont simply cause these home pages to swap positions for brand search in uk (or will it) ? Im worried deploying it immediately could actually destroy the brands current page 1 serps for brand term (since will remove the .com page from the uk serp).Hence i take it its best to build up the new .co.uk sites seo/authority etc first and at least get that sites brand ranking moving up the listings before deploying hreflang on the .com, to then hopefully remove the .com listing in place of the .co.uk for brand ?OR is Gianlucca saying in his comment that correct hreflang usage on both sites should swap the high authority .com no1 position with the low authority .co.uk for a brand search ?Many ThanksDan