When should I have my VPN on?

[Moe]

Unless you trust your VPN provider more than you trust your ISP, don't use your VPN for anything but running your bittorrent client, and only then because you don't want to be hassled with infringement notices.

[Cocobongo777]

Use it everytime, but don't forget about your normal internet activity...
If you will be connected to VPN server all time your provider will see it in provider-logs and administrator can think that it is strange. So time to time you should imitate normal users activity on net

[contrail]

Use the VPN for the profile of a person that breaks the copyright law. Use you ISP for a law following citizen. Never intermix the two and you should be fine. 

[Tech]

I have ExpressVPN on whenever i want privacy....  this may or may not mean "torrents" on a site.

Although u can use a VPN mostly would be for torrents, doesn't mean that's the only thing to use it for.

Some people use VPN's all the time... It's more about what you are doing and weather you decide for yourself. There is no single answer..

[contrail]

Encrypt all the things, all the times.

I agree

Example:

[joew771]

A VPN doesn't encrypt anything. Too bad people don't understand what they are talking about. Like Moe said earlier, use it when torrenting, and otherwise it doesn't matter.

[hypno-potamous]

I have used qbittorent with the advanced option of interface set to a vpn interface name. So it only works when that vpn interface name is active and working. No packets can go out any other interface. Keeps things tidy.