I am working on teaching myself calculus and have a few texts that employ different teaching methods. One covers a short chapter on limits and then goes right into calculating derivatives. Another covers logic, set theory, and rigorous definitions of continuity and limits before introducing derivatives. I started on the first text and am still working through the exercises, but have also been reading the front matter of the other text. Is it more important to take my time and slowly learn the rigorous definitions of everything at this stage, or is it more important to just learn how to do the calculations and learn the proofs in detail at a later stage?