20mg Ami only once in the evening around 8:30pm to ensure I can get up betimes in morning. Seems to work. I wouldn't recommend daytime as has sedating effect which would be annoying at work and definitely rules out driving or use of machinery (the latter doesn't really apply to me, I'm an IT developer, but I suppose rules out late night DIY!)
On plus side it helps you sleep even when tinnitus is playing up.
My neuro has always pushed me towards 30mg when I complain of breakthrough symptoms but I've resisted as I can tolerate the remaining symptoms when they appear and it minimises the side effects. I've tried 30mg a couple of times and dizziness got worse rather than better so I felt like 20mg was my upper limit (although if I'd given 30mg a few weeks it might have settled down). Also a lower dose allows you to keep an eye on your condition better I feel.