When is Isaiah 11:8 supposed to be fulfilled? 8 And the sucking child shall play on the hole of the asp, and the weaned child shall put his hand on the cockatrice' den.


When is this verse supposed to be fulfilled?

I would guess not today (or even tomorrow.)

Furthermore, if in heaven, we are to be like angels, to neither marry nor be given in marriage, where are the children to come from?
Like all prophecy, there will be dispute until it happens (and even then...).

However, millenialists would say that this will be fulfilled in the 1000 year reign of Christ. Sven's diagram shows when that could be.

Your second quote is based on Matthew 22:30 which is about marriage in heaven. Millenialists would say that Isaiah 11:8 refers to Earth.

Here is a commentary I found backing up this idea.