Ras are only useful if they wont be brokken ...
I think starting them at around turn 80-90 or so - well at least when u r sure to have at least PT up at end is soon enough.
At least I wait till connections are a bit "established" - If there are only psoycho civs on your planet ....
But that really depends on playstyles I think
If you make 2 risky RAs and only one comes through, that's still valuable (with PT and rationalism, at least). Holding on to city states is rather difficult in a deity game anyways.