How long hreflang takes to work
Google applies a hreflang change once the change is confirmed on both sides of every pair. Each member has to be recrawled before the new set counts, so the slowest page in the cluster sets the pace. For popular pages the change shows within days. Deep pages on large sites take weeks.
Sitemaps with an accurate lastmod date help Google find changed pages sooner. URL inspection in Search Console requests a recrawl for single important pages. Requesting a crawl for one side only does not complete the pair.
Check a cluster against every rule in this guide.