Those first two kind of don't have much of a coherent plot. They might turn off a first-time reader. Like I said, circle back to them after you've got an idea how discworld works.

No love for the witches? Granny Weatherwax is my favorite character. (Vimes is great but the character changes so much from book to book.)

Anyway, I always recommend reading all the discworld books in order starting with #3 Equal Rites (skip the first two about Rincewind and maybe circle back to them later).