all motors are not starting at same time.

Calibrate the ESCs as per the following video:

Didi you calibrate all the esc's, if yes then enter menu and go to "Misc. Settings-Minimum Throttle:
Adjust the setting so that the motors just keep running when the Transmitter throttle stick is at a minimum."
i.e Slowly increase the value(max is 20 I guess) till the motors begin to spin at the same time.

I quoted this from the manual! Meanwhile I assume you are trying to takeoff in autolevel mode and have configured rest of the stuff properly such as acc calibration,layout etc.