According to Airlineroute.net Garuda Indonesia plans to commence 777-300ER operations in July 2013.
Jakarta-Jeddah will be served by the 777-300ER twice daily (except for Saturday departure from Jakarta and Friday departure from Jeddah, served 1x daily) from 1 July 2013 until 19 August 2013. The regular Jakarta-Jeddah service will then be suspended for the post Eid-Al-Fitr holiday season and recommence on 20 September. The Boeing 747-400 usually serving Jakarta-Jeddah will open a new daily Surabaya-Medan-Jeddah service from 1 August until 19 August.
The 777-300ER schedule between 19 August and to 19 September 2013:
Denpasar-Tokyo Haneda will be served daily with the 777-300ER, this route will then tag on to Denpasar-Jakarta as GA405/406.
Jakarta-Tokyo Narita will be served 6x a week with the 777-300ER and the remaining day is served by the A330-200 (CGK departure Friday, NRT departure Saturday).
For more details please go to the Airlineroute.net page by clicking this link.