When to use 'FIRST' or 'AT FIRST'?

First, let me say that learning the difference between “first” and “at first” is easy. At first, you may think it’s complicated, but after reading this blog, you’ll see just how easy it is.

FIRST

“First” is used when you are listing a series of things or actions:

1. First, take the Metro-North train to Grand Central Station.
2. Next, take the 4 train to Borough Hall.
3. Then, take a cab to our house.

The other items in the list can begin with “Second”, “Third” and so on—although it’s better not to go as far as “Fourth” because it begins to get repetitive. Instead, you can say, “Next” or “Then” (or “Finally”, if it’s the last thing on the list).

People sometimes say, “Firstly” or “First off” instead of “First". These are simply other ways to start a list.

“First of all” is another way to say “First” in a list. But it is usually used to rank the importance of the items mentioned—the most important thing is named first. "First of all" always comes at the beginning of a sentence, followed by a comma.

I don’t think we should have the outdoor luncheon in July. First of all, a lot of people are away on vacation then. And it’s too hot in July to sit outside.

 

In another context, “First of all” helps state a claim more strongly in an argument.

First of all, let me state that I strongly disagree with the proposal. It’s too expensive and won’t solve the problem.

AT FIRST

“At first” means “At the beginning” or “In the beginning” and is used to talk about the time​ things happened—to contrast an earlier state with a later one. It can come anywhere in the sentence.

• At first, I thought I wanted pizza, but then I decided I’d rather have a burger.
• I decided to have a burger, even though at first I wanted pizza.
• I decided to have a burger, even though I wanted pizza at first.

So the bottom line is: “first” begins a list or sequence of events, while “at first” conveys a change of state over time. That’s all you really have to remember. Easy, isn’t it?
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First off [informal idiom]—the first thing one will mention (“off” has no meaning of its own here).