After taking in some of the opinions of others online, here's what I see in a nutshell:
Delaying the replacement of RBG until after the election MAY help energize the right to vote for Trump, BUT
delaying will ABSOLUTELY become THE ISSUE for the Democrats to energize voters for Biden.
Right now, there's really no issue that Biden can press to get out the vote other than "I'm not Trump." Leaving the SC nomination on the table in November hands them a YUUUUGE carrot to get Democrats to vote.
I think the best thing Trump and the Senate can do now is press for the nomination before November, which totally diffuses the issue. And hopefully the Dems spent a big chunk of their campaign using that as an issue, reducing the resources spent on others.
It'll be interesting to see what Trump's administration decides to do. No matter which way it goes, the media is going to pounce and relentlessly try to bash Trump over it. So, there's really no difference from that perspective no matter which way he decides.