Just to say that my last experience of waiting until 3 days before was highly stressful as it didn't happen until about 3 hours before expiry, as per my previous posts.
But - Good news!
Since Rex's last post I have continued to receive the dreaded 'The SSL certificate for “cpanel” on host.domain.com” will expire in less than 30 days.' emails on each daily upcp cron execution. Service ssl certs are due to expire on the 9th Feb i.e. in 6 days.
However, today I was given a new yellow box in WHM at the top right 'click here to update to 10.0.8' - which I duly did.
Part of this update runs checkallsslcerts which has now installed the service ssl certs without issue *more than* 3 days before expiry - confirmed in the logs. Also confirmed on another server which was experiencing the same issue, but with expiry in 23 days.
Phew, no more seat of the pants last minute crescendo stress.
For me, this thread is now solved.
Thanks Rex & Anthony.