There are only, what, about six weeks to go? Certainly all the funeral arrangements will take a week, assuming they don’t follow Jewish practices and bury her today. Heck, Schumer will probably push for her to lie in state for a month before being drawn in a one-horse carriage to every state capital.
Smart course is probably to nominate someone and see how far we can get without unseemly haste. This is going to be a stark election issue for both sides. Let’s see where the cards fall on November 3. I think most moderate voters, disinterested in this particular issue, would react negatively to anything that seemed unfair due to extreme haste.