You should keep utility and credit card bills for 60-90 days because that is the maximum lenght of time to report any disputes. For credit cards, keep at least a year if yo … u purchased any deductions. 12 people found this useful.john gavino.nswer 2: Anywhere between a few months and two years depending on the type of program you choose. An Associate's degree would take at least two years for completion, whereas a medical coding and billing training at a vocational school can be completed in a few months' time.