Also something to note, you'll hit a lot of engine limits building a TC map. You'll have so many dynamic entities that you'll have to use details sparingly (Even more so than Hydro as hydro was made before recent engine limitations got decreased), including water indices (which have nothing to do with water, incidently). It's to do with how the engine cuts up brush faces into triangles.
I would recommend only very experienced level designers go for a TC map as it's going to push your limits for balanced map design (knowing the game in and out and predicting what will be good and bad before it's even play tested so it doesn't bomb right out of the hat), the development process (because cutting corners is less forgiving in a map where there are so many variables), engine knowledge (water indices and lightmaps, using layout to control line of sight for optimisation purposes and skybrushes to seal areas without cutting up visible geometry), time/patience and entity knowledge/ability to understand the I/O flow.
Doing any other map will be far more productive for you in terms of A: Learning at a respectable pace B: Finishing a project and B: generally getting experience through an entire development sequence for testing and getting feedback.
A good learning curve would be KoTH > 5cp > payload. Increasing the load in terms of scale, entity knowledge and I/O flow, number of objectives to balance, spawn room sequencing and balancing each time.