You may want to specify exactly what CST means. I assume you mean China Standard Time, but IIRC China calls it Beijing Standard Time (to rub in the fact that yhey're totally ****ing over Xinjiang province, I guess). Also, China doesn't observe Daylight Savings Time (or Summer Time) so the time differential to the US fluctuates. The best way to be precise about what time you're talking about is to use Universal Time (UTC).
And just so you know, many American poker players keep weird hours so they'd actually be more amenable to 7am-8pm Beijing Time than they are to 7am-8pm in their local time.