10 days if you do all the previous homework
Good niche (not only a wide content niche but a niche you are involved in) for not being out of ideas or fed up of spending hour making videos in a month
Having a list of similar channels to follow, study and "stealing" viewers
Having at least 10 long videos o 100 shorts done (and be ready to throw them all to rubbish if you detect that they are bullshit)
Consistency in all the work a channel need (study analytics, check all the details, create new content daily)