While this is unquestionably a great sign for overall turnout, it was also just the day-1 data point so far.  Let's see if turnout continues to be high the rest of the week or if it trails off some.  It might be this indicates massive turnout overall, or it might just indicate more front-loaded turnout than we've seen before.  A lot of people who are inclined to use early voting might have opted to do it ASAP, rather than waiting a few days.