السلام عليكم ورحمة الله وبركاته A person committed a huge sin and intends to take the hadd punishment (death) but wants to wait some years (30 for example) to do righteous deeds. If he dies before managing to take the hadd but truly had the intention to take it, will it be written for him?

Just repent to Allah (subhanahu wa ta'ala). Repent to Allah, and what Allah has not exposed of you, do not expose yourself. I am assuming—and Allah knows best, because if we were to answer this in a lecture it wouldn't be enough—but I am assuming that this would be fornication, for example. The Messenger told the Sahaba when Ma'iz ran away after being hit, "Why didn't you let him go?" (or as he said, sallallahu alayhi wa sallam). The fuqaha took a ruling from this that they should leave someone alone if he repents and keeps it to himself. However, if it is something else like stealing, then you should give it back to the person because these are the rights of others. There are many violations, and Allah (subhanahu wa ta'ala) knows best. If it has to do with the rights of others, give them their rights back. Barakallahu feekum.