A friend of mine reported getting charged yesterday too. So presumably that means things are getting into gear.
Check that thread Wintersong linked. It seems more likely that you're just seeing the results of Stardock verifying the credit card. Real billing will not happen until beta bits are posted on Impulse, which we shouldn't expect to see until sometime in June at the earliest. I don't gamble, but I'd almost bet that the devs will make an announcement here when they start charging our cards for real.