For me, I got cli's on comenity cards after nine months. Thereafter, I have received cli's every 61 days. For Synchrony, cli's for me have no patterns. I get them sometimes when I ask, and other times I'm denied. Occasionally, I'll get an auto one, but that's rare. But I see people getting increases much more often, so maybe that's where you'll fall. I don't know how long you've had your Kohl's, but you can hit the luv button every four months for an increase. They changed things up last July, where you can request an increase on your online account. Hope this helps. 
Synchrony can be 4 months for some people.
