But I don't just want the units currently available. I want the currently available units in order of the date they became available.
That's not what its designed to do............it set up to show you what is available for the date you have set for your battle so something that is available for the entire run of the OOB could be right beside something shiny and new. It was never designed to show units in order of the date they became available........it looks at the entire OOB and shows you what is available for the month and year you have selected