In order to have a logically possible world without any subjects who experience anything like time’s flow, and still have B-theoretic temporal relations such as ‘earlier-than’ or ‘later-than’, one simply has to be a realist about B-theoretic properties, and state that they inhere some substance.
If this is right, then the nominalist cannot explain how their could be a logically possible world in which no being experiences the flow of time, and in which it is the case that there are different states of affairs which, if there were a being which could experience time’s flow then it would experience a flow of time in that world. In other words, the nominalist must say that there is no logically possible world in which there are no persons and in which a ball is flying through the air from one point to another point (or else in some direction without a beginning edge or an ending edge of the trajectory). This is because the nominalist will deny that there are B-theoretic properties mind independently (I expect) and thus the nominalist may be stuck with a puzzle here and simply opt to bite the bullet and deny that a logically possible world in which successive states of affairs are objectively ordered B-theoretically exists.
However, given a methodological rule which I think should be employed when doing modal logic, one should always differ to enriching rather than impoverishing modality, so that unless or until there is some defeater for the possibility of some proposition P, one should accept that P is possible even if it is beyond their capacity to imagine or even conceive of it. This rule, if the nominalist accepted it, could be turned against the nominalism of the nominalist such that it provides a methodological impetus for abandoning nominalism and accepting substance realism.