From the BIMAN website.
In order to replace the aging aircraft and mordernize the fleet with new generation aircraft, Biman has signed agreements with aircraft manufacturer The Boeing Company on 22 April 2008 and 30 May 2008 for purchase of 04 new 777-300ER to be delivered in 2013, 04 new 787-8 to be delivered in 2019/2020 and 02 new 737-800 aircraft to be delivered in 2015.
No mention of the ex Cathy/Singapore 777-200s.
MAN OPS do you know the transit timings at MAN?