Every time I tried to regulate my sleep before/during a long-haul trip it resulted in the worst jet lag imaginable.

For me, I lead a normal sleep pattern until arriving at the airport for the trip. Then I enter what I call the "airport time zone" when, basically, I just do whatever I feel like doing. It works like this:

If you feel like eating, eat. If you feel like drinking, drink. If you feel like sleeping sleep. I guess you get the point.

Once arrived, I do tend to sleep a few hours if I have a pre 7-am arrival until around 12pm-2pm. Then it's back to normal sleep pattern.