SpaceX today said its planned constellation of 4,425 broadband satellites will launch from the Falcon 9 rocket beginning in 2019 and continue launching in phases until reaching full capacity in 2024. Current satellite ISPs have latencies of 600ms or more, according to FCC measurements, but SpaceX has said its own system will have latencies between 25 and 35ms.
See https://arstechnica.com/information-technology/2017/05/spacexs-falcon-9-rocket-will-launch-thousands-of-broadband-satellites/ 
With latency as low as 25ms, SpaceX to launch broadband satellites in 2019
Satellites will function like a mesh network and deliver gigabit speeds.