I wait 1-3 months, but then update. It used to take way longer, because Amazon's Elastic Beanstalk platform would take longer to update, but I've now changed to Platform.sh and the transition should be easier.
It has been very backward-compatible (i.e. stuff that works in 8.n also works in 8.n+1; and unless you use exotic functions or are relying on special functionality, it should work for you, too).
Once I'm at 8.4, I would slowly update the code / syntax with rector and the assistance of phpstan.
For framework updates I wait 1-2 patch versions before updating, because of composer dependency problems and sometimes bugs do still find themselves into new releases (e.g. I would wait at least until Symfony 7.2.1 before upgrading from Symfony 7.1.x).
I can see it now:
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