He certainly didn't start sleeping with hot women only after deciding to run for president, but he absolutely did make a payoff to someone he [allegedly] slept with ten years earlier during the middle of his campaign. Hard to argue the timing is unrelated to campaign objectives, even in the likely event the Trump Organization paid hush money to other people related to other disputes or allegations long before Trump established himself as a political figure,

Considering he's a serial adulterer it might not be hard to show intent if this is the only case he tried to hush in this manner. If this is the only instance in which he committed fraud to hide the payment it might set an important timeline link between his campaign and the case.

Since the affair happened in 2006, I strongly doubt he went back in time to sleep with a porn star.