As a general rule, the more threatening they believe someone to be, the harder they dial up the volume. They still talk about Hillary and she's not even running.
But it's never too early to start a smear campaign. Afterall, as we all know, it's a well established fact of science that a wrong thing they've been saying for eight years is more true than a wrong thing they've been saying for two weeks. So smear early, and smear often.