Oil based finishes dry/cure in two steps. First the thinners evaporate and the finish becomes tack free. Then oxygen begins to combine with the varnish and curing begins. It's the curing that makes the finish hard, durable and develops full adhesion. This curing process can take 3-4 weeks depending on environmental conditions and how thick a film was applied. As long as it is emitting and odor, it's still curing.
You can lightly sand with a 24 - 48 hour drying time. "Rubbing out" should not be attempted until the full cure time has elapsed. But keep in mind that urethane is added to finishes to make them more resistant to scratching. Sanding, or rubbing out, is scratching. Poly varnishes will never be any more glossy that they are right off the brush.