As far as I have observed, In formal contexts, it is common to write the full title or term and then provide the abbreviation whether in parentheses or along the main sentence using "henceforth" or "hereinafter". Take a look at this example from an UNESCO convention (1):
"The General Conference of the United Nations Educational, Scientific and Cultural Organization hereinafter referred to as UNESCO, meeting in Paris, from 29 September to 17 October 2003, at its 32nd session,"
Furthermore, I found 'HART PUBLISHING STYLE GUIDELINES' helpful:
2.10.4 Abbreviations and Acronyms
It is best to give the full name of an Institution or Official Body in the first instance and indicate in parentheses the abbreviation or acronym by which it will be referred to in the following text: The Department of Trade and Industry (DTI)
NB it is not necessary to use quotation marks within the parentheses in such instances.
If the majority of your readers or general usage commonly uses the abbreviation or acronym eg, NATO, you should consider whether, on first use, the abbreviation should be expanded, ie, NATO (North Atlantic Treaty Organization).