I'm of two minds on this. I think an impulsive suicide is NEVER a good idea, at any age, at 9 or 90. Suicide should be approached with careful thought and should never occur in a state of high emotion. It is, after all, very much a one way street.
Having said that, I think it is generally possible to unfuck your life before you turn 25, but that once you pass that age it becomes increasingly difficult to do so. Time simply starts flowing against you.
Then again, I must admit the me who attempted suicide at 17 would tell the me offering such advice (currently in my mid-50s) to fuck off, and perhaps that earlier version would have had a point to do so.