so what would he receive notification about it from him
, or from him
Boot time from a particular user will depend on the "thickness" of its Internet services and how many tabs he has opened at the same time in the browser. And how loaded his computer, maybe he mines bitcoins in parallel.
And decide what exactly do you mean by "page load time".
In the article on Habre how to measure the time the page is open,
the aspects of when we can assume that the page is loaded.