Jennifer, I was also told the earlier it was taken after diagnosed the more effective they believe it is. Unfortunately (maybe?) I've stopped and started it twice, At first it made me weak, I got past that and it was ok, but started having so many gastro problems I was blaming it on the Rilutek. I even thought that it was maybe to blame for my loss of taste, but it seems not.
Now, I'm currently without insuracne for prescription coverage, so again I'm not taking it. I've got a couple of months worth sitting in the medicine cabinet, but I don't want to take it if I'm not going to keep it up this time.
Even if a person was going with the assumption that it would only afford them less than 6 additional months, who knows but what those months would really matter? What if there was a grandchild expected, etc?
So, I think if the person does not experience too many unpleasant side effects, and they can afford it, it is completely worth taking.