Hi
Here is a sample of using appsink:
Gstreamer decode live video stream with the delay difference between gst-launch-1.0 command and appsink callback - #6 by DaneLLL
You may apply your pipeline and give it a try. Generally it generates timestamps in gstreamer framework. If you need the timestamps in kernel, maybe you can try jetson_multimedia_api. 12_camera_v4l2_cuda is the sample for capturing frames through v4l2.