Why 7 days for Creation?

And do your JW spiritual guides teach that the universe was created in six thousand years?

The Abrahamic religion teach that the universe was not completed until Adam, the first true human being was created six thousand years ago, but they do not teach that the universe, which began with the Big Bang some 13.8 billion years ago, was created in six thousand years.

Gen1:1--God CREATED the heavens and the Earth.

He certainly did, and we live in the sixth generation of the heavens and earth or the sixth generation of the universe.

The six generations are a series of worlds following one upon the other-- each world rising a step higher than the previous world, so that every later world brings to ripeness the seeds that were imbedded in the former, and itself then prepares the seed for the universe that will follow it.

You do know, that in reference to the six days or periods of creation, the Lord refers then to the generations of the universe.