AND, it will depend on who's attacking who.
exactly , last fall there was no indication the price would jump , then Harvey, Irma , Jose and Maria came calling and huge amounts of diesel had to be shipped to the coast to keep generators running and crews working to make repairs as well as refineries offline.
just before spring turnaround is an ideal time if you can figure out when that will be , this is when refineries shut down to change formulation and do maintenance , is when the price falls the most , then while refineries are offline the reserves built up go down and the price climbs.
that said today's truck price is 2.66 here that is delivered , if you can get it for 2.46 or lower I would fill also try not to go below 1/4 tank most places want you to take 200 gallons at a time most people have 235-275 gallon tanks so general rule is call when you get to 1/4 so that you are sure you have a few days.
also this would have been the first year in a decade that contracting gallons really made it worth while , in early August when contracts go out they were contracting at 2.26 a gallon delivered around here , truck price was 2.16 so you can see they really didn't think it was going to change much. they were only giving them selves a dime to work with betting ti wouldn't change even mid heating season.