You're no idiot!
When Lautenberg died, Christie called a special election for October 2013 to keep Booker's senate turnout away from his own gubernatorial re-election the following month. Democrats criticized Christie for wasting money, while Republicans criticized him for wasting a chance to appoint a replacement for the remainder of Lautenberg's term i.e. with a 2014 election.
It sounds like 2 laws conflict but Christie could this time try to appoint a replacement for the rest of the term i.e. until the 2020 election.
http://www.nj.com/politics/index.ssf/2013/06/christie_outlines_special_elec.htmlMeanwhile in Mass, Harry Reid and Democratic lawyers found a Massachusetts loophole that they believe allows the clock to start ticking on 150 days after Warren merely
announces her intention to resign. So if she did that next month, the special would have to happen before the end of 2016.
In short, Booker isn't all that safe a pick as far as senate control is concerned.
EDIT: I will be shocked if it's not Kaine.