Unless there are any specific cases being heard right away it doesn't matter. And if there are any cases, they can always be reheard if there's a 4/4 split without Kav.
http://nymag.com/daily/intelligencer/2018/09/deadlines-for-kavanaughs-supreme-court-confirmatio.html
>Yes, a subsequently confirmed justice can ascend to the bench the moment she or he is cleared by the Senate. But the new justice will typically not vote on cases in which oral arguments were heard in their absence. So the longer the ninth justice is missing, the more it affects the Court’s work.
The real goal is to draw out until after midterms where they have to hope the blue wave isn't a flush down the toilet.