I didn't think I'd find myself walking through my interpretation of a story on LinkedIn, but here we are

She told me the week before that I had no empathy

We know the employee has worked there for at least a week.

I knew from the first day she wasn't right.

She turned up late. No message. No apology. That tiny red flag that I tried to overlook because I wanted to give her a chance.

It's possible Nicky means the first day after being told she has no empathy, but the talk about wanting to give the employee a chance tells me that it's referring to that employee's first day on the job, which we know was over a week ago.

Given a lack of any other details about the employee's various wrongdoings, I'm led to believe that being late was the most egregious thing she did. Ergo, fired for being late over a week ago.

You are free to engage in a discussion if you disagree with my interpretation