The best known and attended synagogue in Saigon is certainly Chabad, located in northern District 1, not too far from Saigon Zoo. Check out the exact location below:
Chabad of Vietnam: 5A Nguyen Dinh Chieu, D1
It is open every day from 9:00 AM to 9:00 PM with a Jewish library.
The Minyanim for Shacharit during the weekdays are on:
Sunday - 8:30am, Monday and Thursday 7:30am.
Friday night - candle lighting on time, than Mincha, Kabbalat Shabbat, Kiddush and Dinner.
Shabbat Morning - Shacharit at 10:00am.