He will curse at the Heavens and even at Gods (who actually exist and have their own will) although his cultivation base is as low as Golden Core Stage or Nascent Soul Stage. This actually makes his Heavenly Tribulation difficulty increase.
It won't take long before you realize that you are reading a story about a villain. I mean, in one of the first arcs, just after he becomes a Rank 2 Warlock, he orchestrates a big masterplan so he can become a Rank 3, in the very same way many villains in other stories do, using elements such as the power of fate, a little righteous protagonist and his rival, and a great war between entire civilizations.
Basically, be prepared to wait ~350 chapters for him to reach Building Foundation Stage and ~420 for Core Formation. It doesn't seem that slow? I can agree, but by chapter 2600 he is still in Spirit Transformation Stage (the 5th realm of the 8 known realms) ! It is just like if by the end of ISSTH Meng Hao was at Spirit Severing Stage.
Even if the novel isn't focused in pure cultivation, the cultivation progress and speed still reflects the progress and speed of the plot. If the novel really only has 8 realms, how long do you think it will take before the novel finally ends?