My Doctor has me on 5mg Valium, which I can take as soon as I have symptom onset or bad enough symptoms (I try to wait until I get to the numb hands and feet stage, rather than just take it for discomfort). It kicks in within 20 min and of combined with breathing (I use the relax application on my phone to counter the hyperventilating), can knock me out (if I'm laying down trying to sleep) or get me functioning normally (if I'm trying to do my thing).