The time change in the car signifies the precise moment The Woman calculated she could have changed the outcome if she had just altered some events after that moment to get home sooner. Time gets weird from that point forward:
-her phone conversation is abruptly cut short; it was presumably longer
-the gas attendant is just standing outside the car when she drives away, a conversation that happened was apparently "cut out" in this version
-she doesn't get pulled over by the cop checking cars like everyone else
-the traffic light changes directly from green to red on the opposite side so that she hits all green on her way home.
By changing all this, she gets home in time to save her daughter (in her head).