This can vary by client but in large part benefit is realized the moment a client decides to move forward.

For most clients they will benefit immediately due to their federal tax liability in the previous year, in the current year, and/or upcoming tax payments.  They have either already paid federal taxes that can be reclaimed; and/or can reduce or even eliminate payments that would be taking place in the near future.   Thus freeing up cashflow immediately and making the benefit in most cases instantaneous.