Be sure to login to all alts prior to levelling main

[Gbyrd]

This way you can gather rest xp.Otherwise it won't start

[hackerlol]

The first character I logged into, my main, upon legion launch had no rested XP but as soon as I logged into the other Alts for the reason you're saying I noticed that they already a slight amount of rested XP stored up.
I think you only need to login to any one character to 'trigger' rested XP on all the characters on the account which are at rested zones.

[Gbyrd]

The first character I logged into, my main, upon legion launch had no rested XP but as soon as I logged into the other Alts for the reason you're saying I noticed that they already a slight amount of rested XP stored up.
I think you only need to login to any one character to 'trigger' rested XP on all the characters on the account which are at rested zones.

I am not so sure about that, but i rather be safe on this end

[Bloodmgx]

Would have slipped my mind if I didn't read this thanks.

[Mahizzta]

Confirmed. You have to login to get rested