With the tetragrammaton the Jews used two different sets of vowel, with one set of vowels they would say "Elohim" and with the other set they would say "Adhonay". Only when combining these vowels with the tetragrammaton could anything resembling "Jehovah" be pronounced.
The first recorded use of the word "Jehova(h)" was in the thirteenth century by a Spanish monk, Raymundus Martini in his book Pugeu Fedei.
This information can be found in the old bOrg book, "Aid to Bible Understanding" on page 884, the last paragraph on the page.
I do agree with cappytan on this, there are more serious issues to criticize the bOrg on.