Tahajjud: Duas at tahajjud can literally be answered the same day. Even if once, Wake up 30mins before fajr, Stand before Allah with all of your problems, prayers, and aspirations. Pray for anything with firm & belief. You shall witness miracles with this act of Ibadah.
Kun Faya kun, If Allah is making you wait, It does not mean that He is punishing you. Rather, He want to hear your voice over and over again, He is waiting for you to pray so that He can answer your prayers with His "Kun" and do not stop praying untill He says kun to your duas.