The Democratic National Convention to select their next presidential nominee will take place July 13-16, 2020. Someone might have a lock on it before then but maybe not too far before then. In any case, 7/13/20 is 1 year, 5 months and 15 days from now. I do not have to start thinking about whether I want it to be Bernie or Beto or Elizabeth or Kamala or any of the 7,244 others who will toss their chapeaus into the ring or be seriously mentioned.
In fact, I can wait at least a year before I have to start seriously thinking about which person I want to see get the nod. I can wait to see who else becomes possible and what all the contenders have to say, even about issues that do not yet exist. I can wait until the competitions and primaries and debates and — most of all — the inability to raise money whittles the field down to a dozen or so.
Right now, I'm thinking I won't pay much attention to this matter until a few weeks before the California primary, which will occur on March 3, 2020. That's like thirteen months from now.
As an aside: I'm not 100% sure of this but I believe the 2020 Comic Con International will be held July 23-26 with Preview Night on 7/22. So you won't have to choose between watching the Democratic Convention and attending whatever panels I do at the con next year. The Republican National Convention will be held August 24-27 and I have a hunch they won't be nominating an incumbent unless it's President Pence.