The easiest way to find Mint flights is actually through google flights.
I use the jetblue "where we fly" to determine which routes actually offer Mint.
Then I enter those airports into google flights->One Way (roundtrip won't show any results unless there are available Mint flights on both dates)-> Business Class
Mint is considered business class on google flights so if you then filter by Jetblue in the "airlines" tab you will be left with only Mint flights.
You then can use the "Price Graph" feature to scroll through all the dates that have Mint flights available (it will only show the cheapest available until you select the date if multiple flight exist for the same date)
I then use this info to book it through the Jetblue website.