Time , IMU's , Arduino UNo , PLEASE HELP !!

Hello

I have a question and i wish someone could help me with it.

I am using an Arduino Uno + IMU(9DOF Sensor Stick)

I would like to know the time the data is captured to plot Acceleration vs Time

Below is my void loop()

could i assume that the difference in times that i am printing as the difference between the first set of data reading and the following ?

I am looking forward

timestamp = millis();
        Serial.println(timestamp);

        //Read the Accelerometer , Compensate & Scale
        Read_ADXL345();
        Acc_Compensate_Offset_And_Scale();
        Serial.println(Acc_Data[0]);
        Serial.println(Acc_Data[1]);
        Serial.println(Acc_Data[2]);

        //Read the Magnetometer , Compensate & Scale
        Read_HMC5883L();
        Mag_Compensate_Offset_And_Scale();
        Serial.println(Mag_Data[0]);
        Serial.println(Mag_Data[1]);
        Serial.println(Mag_Data[2]);

        //Read the Gyroscope , Compensate & Scale
        Read_ITG3200();
        Gyro_Compensate_Offset_And_Scale();
        Serial.println(Gyro_Data[0]);
        Serial.println(Gyro_Data[1]);
        Serial.println(Gyro_Data[2]);

        Serial.println((millis()-timestamp));