Check the Sensor Fuse in Fuse Box.
It is located on the left side of the driver seat near the drivers foot. Fuse costs Qr-5/- only.

Due to this fuse being faulty, transmission is delayed by 2-4 minutes.

Alternatively inorder to Shift the gear I tell you a trick.

* Donot Continuosly press the accelerator.
Press for 15 seconds and release for 5 seconds.
Again Press for 15 seconds and release for 5 seconds.
Again Press for 15 seconds and release for 5 seconds.
See the gear shift.....
You can Follow this method till you check the Sensor fuse.

I experienced the same problem.