Originally Posted by
maverick17
You should be fine with that amount of time. Immigration is 5-45 min at worst, if more than 20 min your bag should already be through anyway. Then 5 min walk to the domestic terminal. So even if the immigration queues are really long, you should still be at the Jetstar counter about 45-60 min before your flight.
Jetstar and some other LCCs have nasty clauses that their check in closes 30 min before departure. At least this is the case in Singapore.