I need help

Please help; I have a register where i enter records including current date, start date and end dates as part of the records. I would like to create a validation micro flow that will prompt display of an error message if you try to enter a date which has already passed. How do I do that?
1 answers

option 1) define on change event and workflow to check the date against current date and create vallidation message option 2) define before commit event on entitiy, to check and create validation messages (on multiple fields if need be) option 3) define the checking as part of validation on domain-object