When did the timeline anomalies start?

I think the timeline anomalies started right at the beginning when Emily's phone screen cracked on the way to the party. That's why she was not only having a hard time hearing Kevin on the phone, it seems like the conversation between the two was strange. It makes me think that the phone call at the end of the movie was the same call she took in the car on the way to the party. I really liked this movie.