This usually depends on their volume of work. They can respond as fast as within a couple of hours, but they can also take a few days. This also depends on your case, as sometimes, they will escalate your case to a different department in charge of that particular situation (such as their Hacks team), and will then wait to hear back from them. Regardless, unless they closed the ticket without answering it, you shouldn't bump your ticket, to avoid infringing on their Customer Support interaction policy.