Should I do Nameless king after I beat the game?

I just finished archdragon peak yesterday and was gonna go fight nameless king today, but I was thinking.

From what I gathered, he's the hardest boss in ds3, and I come from elden ring where malenia is the hardest boss. And because I knew she was so difficult, I saved her for after I beat the game, so she was kinda like the last obstacle to finishing elden ring.

Now what I wanna know is, is nameless king THAT hard? I have beaten most bosses first try, only boss I really remember struggling with was pontiff, and even he only took me 3 tries. So is Nameless king like a massive step up from those and I should save him as a last obstacle after seeing the credits or should I just do him now and continue with the game afterwards? (Im at the beginning of lothric castle)