Thomson Airways plans to fly its first Dreamliner 787s on July 8 between Manchester and Florida and Glasgow and Cancun.
It has apologised to passengers due to travel on July 1 and 7 who will just miss out.
The 787 was due to come into service from today but following the grounding of the aircraft in January, Thomson had already confirmed that it would not be launched until at least July 1.
The operator said passengers who will now have to fly on Thomson Airways 767 long haul aircraft to Cancun and Florida will have their 787 supplement refunded.
"We understand that this news will be disappointing for those customers looking forward to flying both legs of their journey on the 787 Dreamliner, but we are pleased they will be able to experience flying on the 787 Dreamliner on their return journey," it said.
Thomson said it was currently working closely with Boeing and hopes to receive the first of its 13 Dreamliner aircraft at the end of May.
