I agree, July 21, that's only 3 weeks. I've had items from china arrive within 7-10 days, however that's not the norm, it's usually more like 3.5-4.5 weeks. I would at least wait until August 21st before contacting the seller again, and give them a couple of days to respond.
Remember you have 45 days from the date the item was paid for to open a dispute.
So I wouldn't be so quick to jump the gun, if the seller doesn't respond or provide any information and tracking hasn't updated I would then open a case on August 28th. That's 5 weeks. Which I think is a fair amount of time.
Again that's just me personally, everyone handles things differently.
Best of luck in whatever you decide to do.