Re:

As I understand, whether NC is clear has nothing to do whether the applicant is a primary applicant or a dependant, and NC is an independent process for each applicant, so there is no time frame as to how long after the primary/dependant applicant's NC is cleared, the dependant/primary applicant's NC would be cleared.

One of my friends, hu*****and(primary)'NC was pending 2 years after his wife(dependant)'NC cleared. His NC cleared after writing to the first lady.

Another friends of mine, primary's NC cleared and got GC, dependant didn't get GC until 1 and half year later, I assumed that her NC cleared 1 and half year later.

Good luck!