It is a common misconception that you can only accept yourself or only change, but acceptance is actually independant from change. This missconception comes from people thinking that acceptance means to do nothing, which is where problems arise. You will have people that believe acceptance of faults and weaknesses means not changing their faults and weaknesses.
Acceptance actually leads to change. For example, the journey for addicts to combat their addiction begins with acceptence. And then when addicts seek help, the therapist does not congratulate them for acceptance; the therapist also encourages and helps the addicts change. Those who do not accept that they have a problem do not change.
To answer the question, you should always accept yourself, and accept everything about yourself. But remember to accept who you are in the present, and not the past. There is no way to rewrite or change history in the past, so focus on accepting the present. You were a differnet person in the past compared to who you are in the present, so there is no point in looking back, in holding guilt for past mistakes, and in trying to change that past. Instead have self compassion toward your past self, acknowledging that blaming your past self does nothing, and then change. You were never perfect before, and you are not perfect now. But you can keep reiterating, fixing, and growing. You do not start the game of life at lvl 100; instead you are at level 1. You can either have a great spawn with good loot or a bad spawn with cursed gear and debuffs. The goal is to level up, cure those debuffs, and unequip the cursed gear.
You might feel like you are so messed up that, there is no hope in changing. But those thoughts might be depression trying to convince you that your situation is way worse than the reality, so that you can give up and lose hope. It is intersting because the human ability to accept and change also gives humans the ability to have depression. It was a major evolutionary change in the mind that helps preserve us, and without it, humans would have to rely on pavlovian conditioning and trial and error to problem solve. Learning what you can trust from your mind is powerful, and knowing what thoughts to trust comes from meditation.