'they' do it with experience.
With just under 100 laps under my belt I was lapping just under 9minutes in April in my dodgy old Golf, albeit in the relative safety of a track day.
Best not to bother timing your laps until you actually know where the track goes IMO. Timing = buying armco if you don't know what you're doing. Your M3 wasn't sliding because it was wet, it was sliding (presumably unintentionally) because you didn't know where the track went, or where it would be wet, because there are certain points that always dry out slowly.
09:43 really isn't anything to brag about in an M3 on 888s. I'd keep quiet about that if I were you. Mid eight minutes and it might start to be worth mentioning
With around 20 laps chalked up Hurdy was lapping under 8 minutes in his Golf*.
*warning, Golf may contain modifications and nuts.