Great topic! Thank you for the post.

As the post indicates, firstly is a word most native English speakers don’t use, and many might assume it implies a lesser understanding of the language.

We’re delighted to have readers in many countries. We often remind our readers that this website and The Blue Book of Grammar and Punctuation represent American English rules and guidelines. You may find our multi-part review of American and British English of interest. We may also explore other differences among English dialects in future newsletters.

As the post states, “If you wish to continue writing and saying firstly, you won’t be defying grammatical principles. But don’t be surprised if other people act as if you are. It’s a word most native English speakers don’t use, and many might assume it implies a lesser understanding of the language. Unless you have a specific reason to use firstly, secondly, thirdly, and so on, it’s better to stick with the shorter, simpler, and more commonly accepted alternatives first, second, and third.”

Despite their similarity as adverbs, “first” and “firstly” are hardly interchangeable in all situations. In the first place, one would not say, “I firstly noticed it yesterday.” One might ask, “First off, what are you doing in my home?” or “Firstly, I hope you have insurance.” In the end, “first” is the better choice if you want to avoid criticism from peers and stern looks from professors.

Moral of story- Don’t judge alternate adverb usage as a negative.

The term “first off” is grammatically correct; however, we would not recommend using it in formal writing.