Hi eesen,
I have found this
example program that shows you how to add a timed loop to a synchronized group of loops. Please take a look at this, and let me know if this is what you were looking for or not. My thought is that you can have a case structure that allows you to add to the synchronized group if your start condition is met.
Best of luck on your application, and have a great day!!
Regards,
Ching P.
DAQ and Academic Hardware R&D
National Instruments