In reference to centuries, when should I use a hyphen with early and late?
Note: This post relates to content in the eighth edition of the MLA Handbook. For up-to-date guidance, see the ninth edition of the MLA Handbook.
MLA style generally hyphenates elements of a compound adjective and does not use a hyphen for a noun phrase.
a poet of the early nineteenth century
an early-nineteenth-century poet
theater in the late twentieth century
A compound with mid is trickier, in that there is more than one way to style it.
At mid-century the practice flourished.
In the mid–eighteenth century [use an en dash] the practice flourished.
In early- and mid-eighteenth-century salons the practice flourished.
Or you might decide to leave open a mid compound you would otherwise hyphenate.
In the early and mid eighteenth century the practice flourished.