There’s quite a few threads on this subject already
There’s advice in that thread but also a link to more advice
To specifically answer your thread question... it’s essentially all luck. But posting daily is your best bet for getting subs as quickly as possible for a novel. From my personal experience, I hit 100 subs in a month after posting every day for a week and then going to a 3x weekly schedule. For some people that might seem slow and others would think that was fast. There’s SO many variables to take into account. But posting daily keeps you in the fresh section every day 