We would recommend the Railink train service to and from the airport if you are tight on time. The unpredictability of Jakarta traffic can sometimes be a nightmare. You can get from the airport to city centre (BNI CITY station) and the other way around in approximately 33 minutes. Train schedule is fixed and can be found on the following link (https://www.railink.co.id/jadwal-kereta). A train ticket costs IDR 70,000/person each way. The hostel is around 3 km away from BNI CITY station and may be reached by metered taxi or by motorbike taxi within 10-20 minutes depending on traffic.