I would say you should take the latter. To be honest, IB Math studies does not go as in depth with topics necessary for calc as pre calc. Some of the stuff taught in math studies will not help you in calculus…like at all. I don’t foresee you needing to use venn diagrams for calculus. The route you proposed sounds really good to me because that is the foundation you need to be successful in calculus. Math studies touches the surface with these topics. From my personal experience, since I have taken all these courses except for trig, the only thing math studies teaches you that you may or may not learn in pre calc would be optimization. But other than that you are much better off not taking math studies. I do know that Math SL is much more comprehensive and if you can you should take that but honestly, just skip math studies.