Speaking from my personal experience, remssions can last for two or three months, or even years, and remissions, for me, have been complete cessation of pain. When the pain has returned, it has started up small, little twinges becoming big twinges, until finally one big zap and you know it's back. The amount of time between the first little twinge and the first major zap can vary hugely, plus if a major flare up is approaching I can usually feel my cheek/jaw area pulling and tightening - usually, but not always.
Having an intense dislike for the side effects of the meds, I have tended to put off starting on them again in the early stages, figuring that the longer I can delay taking them the better I feel. But with hindsight I really don't think that's the right thing to do, for me anyway, and I think there are others who would agree with that, especially remembering that with some meds (Tegretol, for instance, which is what I take), when you first start taking it, it can take three weeks of regular dosing before you start to feel the benefit of it. If you start taking it right away, maybe you can calm and settle the nerve before it flares up into the major zaps - and I think it's worth trying for that reason.
It is roughly 15 years since TN first found me, I am currently in remission, and these days when I feel the slightest twinge, I make a conscious and decided effort to RELAX, physically, mentally, emotionally, spiritually, as I believe stress (inner or outer) to be a major trigger for fresh cycles of TN. The first thing is to unclench the jaw; we all tend to clench up, often even when we're not stressed, and I think that has an effect on the nerve, so I am always, always unclenching whenever I catch myself doing that. Plus, when feeling twinges, keep mouth slightly open all the time, even when sleeping, so that jaw really is relaxed. This helps to keep you from unconsciously clenching the jaw. Lie down, meditate, or even medicate a little, take a hot bath, play relaxing music - whatever it takes for you to just lay everything down and focus on not stressing - in effect, find a happy space. Hopefully this will help, but I assure you that we all struggle with worrying about that awful pain returning, it's a constant theme, so you're not alone with it, you just have to find what works for you. All the very best.