mrs. nd_eric_77 took our daughter to CGK when she was 10 months old (daughter; not mrs. nd_eric_77). The baby had her own seat and slept most of both flights. The adjustment was much harder on my wife than on our daughter. It did help that they had an overnight stopover in ICN to get some sleep at the hotel.

It seems that babies adjust to jetlag pretty well. Big piece of advice is to be very careful during the boarding and deboarding processes. A dude dropped his laptop bag from the overhead bin right onto our daughter's head when they were deplaning in Jakarta. Our daughter was startled and cried a lot but did not receive any permanent injuries. My wife was understandably furious but controlled herself.