How soon can I set equipment after concrete is poured?

Concrete needs to be completely hydrated which is typically 28 days with standard concrete.  Concrete could be hydrated faster than 28 days but would need to be tested to verify full hydration.

How do I prepare my concrete foundation for grouting?

Remove all laitance with a chipping hammer.
Make sure the concrete is properly hydrated.
Be sure the concrete is free of any oil or contaminants.