I actually have a trip to Bali in two weeks time. I contacted the hotel (Sofitel Bali Nusa dua) to ask if I could postpone/cancel the trip should the volcano erupt and they replied saying it is possible.

HOWEVER, the hotel did say they will not allow any cancellation or amendments as on now as the situation is still safe and flights are operating as per normal. Thus, all I can do is wait and hope for the best. I believe the volcano will erupt within the next week but that's just my 2 cents worth.