Hi - I'd suggest you post on the NCL board (maybe you have - my bad).. But with Freestyle there are no formal nights and pretty much anything goes. Most cruisers dress business or resort casual though (I think). You might want some fancier attire for the specialty restaurants if you want to try them and enjoy a nice evening.
Have fun on your cruise.
All I ask is a tall ship and a star to steer her by; John Masefield
Carnival: Glory 2004, Destiny 2008, Splendor 2009, Freedom 2011, Valor 2012, Dream 2013
Celebrity: Summit 2011
Princess: Ruby 2010, 2014, Caribbean 2013, Coral 2014, Regal 2014, 2016, Royal 2017
Star Clippers: Royal Clipper 2015
I posted my formal attire question and got good advice. I am also checking
out the pictures of other cruisers to see what they are wearing. I am also going to ask the person who we booked the cruise with.