Many airlines use a premium checkin at CGK T2. It is at the end of the terminal, next to the SQ checkin in counters. This area has own checkin (will take luggage) and private immigration. From immigration, you exit right into the Premiere Lounge. I just can't remember if JL pax are allowed to use it! Maybe someone else here can verify. If you can, it has never taken me more than 10 minutes to check in, clear immigration, and enter lounge.