For US voting peoples, at what point in the process do you engage in reviewing or forming an opinion on candidates?

While Trump is obviously running in 2020, at this stage the Democratic candidates are announcing themselves and have already started campaigning and giving speeches.

Regardless of if you are voting democrat, republican, or independent in any election, do you start watching the candidates at this stage? Wait until they are narrowed down at the primaries? Wait for the debates between the final main candidates? Or do you looks just in the time before you vote and somewhat procrastinate on who you will vote for?

Everyone is different with this, and I am sure it comes with just what level of interest in politics you have as well.