Can you paint the concrete floor as soon as muriatic acid etching dries?
To test a concrete floor for sufficient dryness before painting you should tape a two foot by two foot square of (clear) plastic film to the floor, wait 48 hours and see if the concrete is darker under the plastic or if any condensation has occurred on the underside of the plastic. If so then the floor is not dry enough. If no condensation or darkness, paint.