You really need to forget your C1 workflow, since darktable’s is so fundamentally different. Pretend you’re a complete beginner. I have collected the best tutorials and other useful advice in my beginner guide:
You will also have to accept that you will probably not get the same level of results for at least a little bit, due again to differences in how they work.
Make sure OpenCL is enabled in the preferences, because otherwise only the CPU will be used. But if the GPU isn’t very fast or doesn’t have much VRAM, it may be better to run on the CPU.