This is the 362nd most frequent Dutch word.
daarvoor
"Daarvoor" means "for that" or "before that" in English, depending on context.
Here, 'daarvoor' refers to the reason or target of needing help, which is the activity of looking for a new house.
Ik moest een nieuw huis zoeken en daarvoor had ik hulp nodig.
I had to look for a new house, and for that, I needed help.
In this context, 'daarvoor' indicates the causative reason related to the effort of practicing and studying that leads to success.
Oefen regelmatig en studeer goed, want daarvoor zul je slagen.
Practice regularly and study well, because of that, you will succeed.
In this sentence, 'daarvoor' is used to express necessity related to the presence of something (the queue necessitating time).