This is discussed a good bit so maybe there's a moment to review the 'rules'.
First, there are only three ways for the 25th to be drawn into play. The President can just say he's go health issues and it's a simple process.
Second, the VP stands up and has the support of the majority of the cabinet. If you don't have the full support of the cabinet? Then you are left to the third method....the House (acting as the 'body').
The House in this case....would have to present 'evidence' and then gather for a vote. Presently, with the Democrats managing the situation....it's Pelosi's situation. It's anyone's guess if she has the votes to manage this.
How many days, if the House is managing this? I'd go and speculate that you could wrap this up in three days. But I'd also suggest that one-third of the Democrats would refuse to vote, or vote against this.
Does Harris have support of the majority of cabinet officers? That's another problem. Fifteen cabinet position, and some might be die-hard pro-Biden fans. You might also have two or three who see Harris as lacking the skills to be President.
If Harris had the eight letters attesting to 'issues' with President Biden....then this would go rather quickly (I would speculate) and it might be over in one to two days, with the House just agreeing.....without a lot of discussion.
If the 25th started to fall into play....would President Biden just resign? He probably would go to several of the cabinet officers and ask them in a blunt way how they were going to 'vote'. Could he fire them if they voiced a problem? Yes, without any doubt. But I would suggest that Biden hasn't shown much history in firing people.
Is this goof-up in Afghanistan the only visible mistake of the Biden administration? Well....that's the key question....you don't know. The news media should have made comments over problems, but generally, they've failed at their responsibility. So you have no idea how bad the situation might be, or how successful Biden has handled problems.
Should they just wait to get out of this mess, and hope to continue on? At this point, the lack of common sense is openly discussed and you have to wonder if more mistakes will be committed over the next year. When you arrive in the fall of 2022...with the mid-term election....could these mistakes be made into a dozen Republican campaign ad's and massively destroy the Democratic chances?
Then finally.....does Harris really want the job? I would argue that she's gotten a glimpse of incompetence within the White House staff, and probably 50-percent of what went wrong here.....were simply incompetent people around Biden. If you don't fire them, you end up committing the same mistakes as Biden made.
One footnote, after Harris moves up to the Presidency, she would select her new VP. Both the House and Senate has to agree to the person. The Senate, with Harris as VP? Well...the Senate is currently 50-50. You would need at least one Republican to flip and vote along these lines. So I don't think Harris would be able to select a Senator, or some far-left idiot. The new VP will end up as a very likeable individual (my take on this).