August 3rd is the last day the governor can call a special election. Otherwise it's just combined with the general election.

I'm not sure if this is even that advantageous for the Republicans. Even during a special election a Republican will likely win, even if it's a less Trumpy one, still a Republican. Seems better than an empty seat.

Unless they have reason to believe a dem would outperform in a special election.

Also since there has been confusion in other threads, Kentucky does not allow the governor to fill a vacant senate seat by appointments, he can only call a special election