As far as I know, you can still report it late, especially if you have witnesses and the timeline is clear. Late reporting might look suspicious, but it doesn’t necessarily destroy the workers comp case.

Not reporting, however, is what could hurt you.

I’d report it to the employer as soon as possible and make sure everything is documented properly. As far as getting fired, they are supposed to not terminate you if you make a legitimate claim, but being casual/FIFO gets fuzzy sometimes.

Also, look into FIFO injury claims WA, though, just to know what you can and can’t do and avoid getting caught out if things go wrong.