The particle-wave duality of the graviton, if it exists, is a concept that arises from the principles of quantum mechanics. However, it is important to note that the graviton, a hypothetical particle thought to mediate the force of gravity, has not been confirmed experimentally.
In the framework of quantum mechanics, particles can exhibit both particle-like and wave-like behavior. This duality does not inherently imply uncertainty in time or spacetime. Uncertainty in quantum mechanics refers to the fundamental limitations in simultaneously measuring certain pairs of physical quantities, such as position and momentum, or energy and time.
When it comes to gravity's effect on time, this is described by the theory of general relativity, which is a classical theory of gravity formulated by Albert Einstein. According to general relativity, the presence of mass and energy curves spacetime, affecting the flow of time. This is known as gravitational time dilation.
The interplay between quantum mechanics and general relativity is a topic of ongoing research and the subject of attempts to formulate a theory of quantum gravity. However, a consistent and experimentally confirmed theory of quantum gravity is still elusive.
It's worth noting that the concept of gravitons and their behavior in different quantum states is speculative and subject to future scientific discoveries and advancements. At this point, it would be premature to draw conclusions about the implications of a graviton's particle-wave duality on time or spacetime.