I saw this too, and was able to get the same results as you, but now I cannot recreate it. Now I can't get it to show any on the 29th, or individual time stamps on the 29th, everything is the 30th and onward.
I saw a post on X claiming data for Monique, but data for Spencer was blocked, so I went and did my own inquest. I found what you found, and was startled. I ALSO saw that the searches on the 29th for Monique were Ohio ONLY, but for Spencer it included PA, VI, and I believe MI as well as Ohio, I think there was even WA in the mix. I found that interesting too.
I read that the number represents a relative percentage compared to the 100% peak viewing time, if I understand it correctly; it is NOT the absolute number of people searching. I find this data VERY interesting, that there is little to no interest until just hours before the murders?