That is outrageous, everywhere I've worked, even if you start part way through the month I've received the pro-rata salary at the payday at the end of the month (whether that's the last Friday, last working day or even the 1st).
In fact when I arrived in my present position I was given my salary in cash the first month whilst everything was put into the accounting system.
I would definitely have her speak to HR about a reasonable compromise and lay on the emotions.
