British Airways has opted for a phased move into the Terminal 5 following its baggage system chaos in its March opening.
Long-haul flights will be moved to the new terminal in three phases.
On 5 June, BA will move 15 daily arrivals and departures, including New York JFK, Bangalore, Beijing, Cairo, Cape Town, Lagos and Phoenix to the routes from the new terminal.
On 17 September, 30 daily departures and 30 arrivals will move into T5 from Terminal 4, adding flights to Accra, Mauritius, Abu Dhabi, Bahrain, Doha, Kuwait, Sao Paulo, Rio, Washington, Dallas, Houston, Chicago, Toronto and Mexico.
By October, 15 daily departures and 15 arrivals will complete the long haul switch to T5.
"This phased move has been planned in the interests of our passengers and the smooth operation of Heathrow over the busy summer period," BA and Heathrow airport operator BAA said in a jointly released statement.
BA and BAA did not mention whether the baggage and IT system problems had contributed to the delays.
The carrier had initially planned to move all but three of its long-haul flights to Terminal 5 by 30 April, but the calamitous opening of the terminal compelled the airline to delay the move.
Terminal 5 opened on 27 March, 2008 and was immediately beset with problems to its baggage handling systems. The baggage handling system, developed by Vanderlande Industries and IBM was part of the pre-opening publicity for Terminal 5. According to BA, staff we unable to log on to the system.
There were also problems with the staff car park meaning staff were unable to get to their jobs in time.
In April, BAA chief executive Colin Matthews admitted that T5's baggage handling technology had not been tested sufficiently.
BA chief executive Willie Walsh told MPs that the carrier has "compromised" on staff training, in a bid to make sure the terminal opened on time.
Currently BA has 60 daily long haul arrivals and departures leaving Terminal 4. T5 is now operating 14 long haul daily arrivals and departures. By the end of October the airline said it will be handling 510 flights a day from T5.