It took me 23 hours (with layovers) to cross the Pond.

Even with no sleep (because I had watched movies on the plane), I still did a full day in London without stopping.
I feel that continuing "to go" is the best way to get one's internal clock somewhat set to local time.
When all was said and done, I managed a grand total of 39 hours from bed to bed.
It was a long, tiring day, but that was not a personal record. The record still goes to my first day in New Zealand http://www.pbase.com/britestar/image/111677869
That New Zealand trip was a time when I learned what it feels like to actually hit the proverbial wall. Never again!!!

However straight from the Heathrow, I left my luggage with the hotel concierge, freshened up in the public ladies room (because my room wasn't yet ready), and then jumped on the Tube. I didn't formally check into the hotel until 12 hours later. My husband says I'm driven, but I feel life is too short to waste a day when adventure awaits.