On Twitter, Google’s John Mueller said that Google processes disavow link files immediately. However, the it takes some time to disavow the links. There is no fixed timeline.
The files are processed immediately. The links are disavowed over time – there is no fixed timeline.— ? John ? (@JohnMu) June 1, 2019
Bing also says that you should disavow links
Bing’s Frédéric Dubut also said that disavowing links is useful if your website has a bad link profile:
Nothing recent published on the blog but our general philosophy on disavowing is that it's still useful, particularly in cases of penalty or just generally bad link profiles. However for most folks it's probably not the highest ROI activity compared to other things like crawl ?— Frédéric Dubut (@CoperniX) June 7, 2019
How to create a disavow links file
The Link Disinfection tool in SEOprofiler detects bad link profiles. It finds links to your site that should be disavowed and it creates a disavow links file for you: