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I received my QS1 in Dec. 2015 and got my first CLI last month. This time I will wait the full 6 months.
If it's part of the credit steps then you should get another increase after your 5th payment, then at 6 months intervals if eligible (not a guarantee, but can happen).
I have never requested a credit increase it has usually just been an automatic increase. I am attempted to try i am up to $1500 CL and started with $300 last July so its been almost 8 months with them and went from $300 to $1500.