SHM phase constant sign

Please look at picture.
My textbook only gives the answer with -pi as a phase constant. But, since we are at "a switching point" on the unit circle, the sign doesn’t really matter. The graphs give the same result whether a positive or negative sign is used. Am I right? Does it conceptually change anything?

Attached Images
File Type: png Screen Shot 2014-06-12 at 5.37.36 PM.png (18.8 KB)

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