Amazon and Google I knew had been around since the late 90s as I used both of them fairly early on. I still have a couple of coffee cups I got as "Christmas presents" from Amazon in early years as thanks for being a customer.
Facebook I started with while it still required a school address.
It does look though as if I started using Netflix in late 2001. So not that much later.
Here's how old these companies will be turning in 2018:
Snapchat: 7 years
Uber: 9 years
Twitter: 12 years
Facebook: 14 years
Tesla: 15 years
Google: 20 years
Netflix: 21 years
Amazon: 24 years
Apple: 42 years
Intel: 50 years
HP: 79 years
Disney: 95 years
IBM: 107 years