It shouldn't be that noticable in Bali ..but there are moslems there and they'll be taking it real slow for about the first week :)till they get used to not eating from sunrise to sunset...
About the 20th of October is when the planes, trains, buses and ferries will be getting full, and the traffic starting to build... and then the week after "lebaran" on the 23rd and 24th October when they all head home...