2nd iteration of all thread groups is to be started after the first iteration of the thread group with longest iteration time is complete. This behaviour is only to be there in 2nd iteration. Not in first, third, fourth or any subsequest iteration.
Need help in achieving this.
Consider using Inter-Thread Communication Plugin.
Example scenario:
Check out SynchronizationExample.jmx plan for a demo use case.
You can install Inter-Thread Communication Plugin using JMeter Plugins Manager