Just FYI, 25 subscriber for less than a week is an exception not a norm. For most, it can take a month or more. Do not take it for granted, many people has not reached that number yet so consider you are lucky
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Also a dive or plateau will inevitably happen especially with longer and inconsistent updating time, some months are also less active than others because of school/workload your audience have.
The "How long" questions is a bit tricky to answer. Variability is high and there are many factors. To exemplify for most of us we need more than 5 days to get into 25 subs, but you don't. Plus, no timestamp is a guarantee for you to reach a certain goal.
Some would simply say you might get to 100 in one month or less judging by update, genre appeal, and initial number; but things happen (maybe something interferes in real life, etc.). What if you don't and you got yourself bummed because it is not what promised? Do not set up an expectation in that way.
Also you update up to 35 chapters a day. If you already have a buffer I could say you can maintain consistent update for the rest of the story, and preferably not that much. Once or twice at max a day, but everyday is more ideal