I think FD put the altered plates on the black Suburban and drove to JD's home. Most men in the cul de sac would have already left for work and most women would only have registered a black SUV going up her driveway and would assume it was JD, if they even saw it.
He expected to kill her cleanly, put her in the black SUV and leave. If noticed leaving, again most would assume it was JD leaving and think nothing of it.
Her own black vehicle would remain in the garage all day because the cleaning lady had no reason to go into the garage. It would have been noticed after 7 o'clock pm, when LE checked and had there been no bloody evidence of an assault, the Silver Alert may not have been issued.
Also, there would have been no need to put her vehicle at Waveny Park.
He would have been long gone to disposal of her body and there would have been no need for a dumpster run in Htfd.
However, all changed when her blood hit the floor of the garage and by description, he does not do well with improvisation, he is more of an over planning spread sheet kind of a guy.