GOD'S WORD® Translation
"I'm telling you this now before it happens. When it does happen, you will believe.

American Standard Version
And now I have told you before it come to pass, that, when it is come to pass, ye may believe.

Berean Study Bible
And now I have told you before it happens, so that when it does happen, you will believe.

Douay-Rheims Bible
And now I have told you before it comes to pass: that when it shall come to pass, you may believe.

English Revised Version
And now I have told you before it come to pass, that, when it is come to pass, ye may believe.

King James Bible
And now I have told you before it come to pass, that, when it is come to pass, ye might believe.

World English Bible
Now I have told you before it happens so that, when it happens, you may believe.

Young's Literal Translation
And now I have said it to you before it come to pass, that when it may come to pass, ye may believe;

John 14:29 Additional Translations ...