First quarter CS major classes... How much is too much?

I am planning on taking CSS342, CSS301 and an elective course CSS337 aka (DATA, ALG, MATH I, Technical Writing, & Secure Systems).

Does anyone have experience taking courses like these in a single quarter? Would you recommend taking CSS360 instead of Secure Systems? Any advice would be great. I don't want to involuntarily kill myself this quarter. Thank you!