GOD'S WORD® Translation
They are created now, not in the past. You haven't heard about them before today, so you can't say that you already knew about them.

American Standard Version
They are created now, and not from of old; and before this day thou heardest them not; lest thou shouldest say, Behold, I knew them.

Berean Study Bible
They are created now, and not long ago; you have not heard of them before today. So you cannot claim, ‘I already knew them!’

Douay-Rheims Bible
They are created now, and not of old: and before the day, when thou heardest them not, lest thou shouldst say: Behold I knew them.

English Revised Version
They are created now, and not from of old; and before this day thou heardest them not; lest thou shouldest say, Behold, I knew them.

King James Bible
They are created now, and not from the beginning; even before the day when thou heardest them not; lest thou shouldest say, Behold, I knew them.

World English Bible
They are created now, and not from of old; and before this day you didn't hear them; lest you should say, 'Behold, I knew them.'

Young's Literal Translation
Now they have been produced and not from that time, Yea, before the day, and thou hast not heard them, Lest thou say, 'Lo, I have known them.'

Isaiah 48:7 Additional Translations ...