Careful making conclusions from sensationally written articles based on
one-sentence tweet from testing under perfect conditions.
"Less than 20ms" latency was not reported, only the words "super low" were reported and that it is fast enough to play games.
(Sub 20ms latency is the goal of the system)
Also see
real-life beta user tests from a few weeks ago. Speeds between 11 and 60Mbps and latencies between 31 and 94ms.
Impressive results especially noting that this is still very early days and things will improve.