Is Donald Trump the first presidental candidate to be called, "presumptive"?

No. Once the nomination is assured, that is the traditional term used prior to the actual nomination in the party's convention. It really would not be wrong to use that term for Hillary Clinton, either. There is a bare possibility of Bernie Sanders winning the Democratic nomination but so remote as to be nearly impossible.

Not by a long shot; As in the last 2 presidential elections it took Kerry, until April, McCain til May, 0bama to July, and Romney almost that long to be called the presumptive nominee.

As far as I can remember. I am over 60. The reason is that nothing is final until the convention. Trump could still shoot himself in the foot.

No, the term has been used for a long time for anyone who is going to get a nomination, but has not actually gotten it yet.

Nope. Jeb Bush held that title when the debates began.

Wonder where he is now?

No.