For better adhesion, it is better to use thin coats, rather than thick coats of polyurethane. Apply the polyurethane a few boards at a time, the entire length of the boards. This prevents overlap shading marks at stop and start areas.

Allow the final coat of polyurethane to fully dry before loading any furniture in the room. And, use felt pads on every leg of every piece of furniture to prevent scratching the newly finished floor and to make it easy to move the furniture so you can chase those dust bunnies.

Good luck.