Grammar of, in dialogue, someone quickly negating a previous word?

Question

For example, let's say that someone says a word, but then immediately "corrects" it to a different word. Do you use a comma, an em dash, or what?

In addition, if it's at the beginning of a sentence, does it count as restarting the sentence (and thus necessitating capitalizing the next word)?

In this example, which is correct?

1. "If, no, when John arrives, he'll have some explaining to do." (comma, no sentence restart)

2. "If-no, when John arrives, he'll have some explaining to do." (hyphen, no sentence restart)

3. "If—no, when John arrives, he'll have some explaining to do." (em dash, no sentence restart)

4. "If-No, when John arrives, he'll have some explaining to do." (hyphen, sentence restart)

5. "If—No, when John arrives, he'll have some explaining to do." (em dash, sentence restart)

Thank you for your help. This is not the same question as the one this is marked as a possible duplicate of, as it refers to immediate negation of a previous word, and does not necessarily involve starting the sentence over.

Answer 1

Welcome to writing SE, Logrun.

Definitely not an n-dash. I'd suggest two m-dashes to set it off, but since you are in dialog, you can play around a lot.

"If--no, when--John arrives, he's got some explaining to do."

^^ That'd be my style. ^^ It sets off the correction on both ends.

But, you can also use other approaches. Here are a couple more options that seem right, at least to me... at least grammatically.

"If... You know what, there's no 'if' about it. When John arrives, he's got some explaining to do."

"If, or rather when, John arrives, he's got some explaining to do."

Answer 2

None of the above. I think you have a crucial comma in the wrong place to get the sense out of the sentence that I think you're aiming for, and also the tense feels dislocated to me. I would use the following:

"If, no when John arrives, he's got some explaining to do."

Emphasis is important in this kind of situation and using italics to put a definite accent on the term the user has decided best fits the situation is, I feel, the quickest way to convey their intend to take John to task upon his arrival.