On Rosh Hashana our fate for the upcoming year is written. On Yom Kippur our fate is sealed. Still that is not the end. It is the Malachim who have the task of carrying out our agenda throughout the year. They are given their assignments on Hoshana Rabba. Hashem carefully guards our "Petek" our signed fate from Yom Kippur until Hoshana Rabba. That means there is still hope to change it since it is still in Hashem's hands.
Why the added delay? Is there something we can do after the gezeirah is signed? Yes of course! While Teshuva from yirah, from fear, can alter the gezeirah before it is signed, only Teshuva from Ahava, from an outpouring of love for Hashem from the depths of our hearts without any consideration for our fate, can break Hashem's heart kiviyachol. When Hashem sees His children leaving their homes to rejoice with Him in the succah and joyfully taking the arba minim without any consideration as to what will happen to them in the upcoming year, how can a loving and merciful father not rip up any bad decree and replace it with one that we will enjoy?
This was the success of Purim. After our fate was sealed and we were delivered into the hands of Haman HaRasha we gave up and no longer cared about ourselves. We totally submitted to Hashem and loved Him without expectation of anything in return. This attitude had the power to repeal a signed decree.
So before Hoshana Rabba don't beg Hashem to change your fate. Forget about it and just enjoy Succos. The rest will take care of itself.