The wide variety of 'takes' on this simple question highlights why it is poor practice. Similar questions arise from time to time regarding the point at which a pilot can/should report vacated. Once again there is a variety of viewpoints and opinions - add this to the ambiguity of "vacate and call ground" and it is no wonder that we see such practices contributing to incident reports. And the incident reports are only the times it goes wrong for some reason.
Phraseology and procedures like this may sound 'slick' but it is much better to be standard, precise and unambiguous - that way there isn't any doubt in anyone's mind about what should happen and you don't get to feature in incident reports!