1 minute difference when you're sat in a 20 mile jam doesn't make much difference. The pratt who decided to move this to a Friday night has obviously never sat on the M25 for 2 hours going nowhere!
If you're going clockwise you'll hit the jam where the M3 joins the M25 and be lucky to do more than 20mph past the M4, on through the roadworks (Jnct 16-18) and on to the M1 junction. Thats assuming there's not been an accident or a breakdown in the roadworks!
If you go anti-clockwise again you'll hit the queue at the top of the M3 which crawls through to the next junction, and will be slow through to the A3 junction. Will be slow again around Clacket Lane, and then you'll join the queue for the Dartford Tunnel - expect at least an hour hold-up there!
Some regular users are now getting so hacked off with Dartford on a Friday that they're going through the centre of London and using the Blackwall Tunnel - not to be recommended though!
Message is leave early (Thursday should suffice!!).