I was really terrified of taking potassium also, so it wasn't until I got to a really bad state and was on and off mfolate because I couldn't deal with potassium sink, before I tried it.
Finally I forced myself to try potassium gluconate (1/2 teaspoon = 270 mg mixed in water, taken with 1/2 a banana, you need to have food with it), and it was a life saver. Now I take it about 5x a day, plus 1-2x at night. I've been doing that for more than 6 months and so far so good, although I wish I didn't have to. Unfortunately, I do.
Since I started mfolate, some of my thyroid levels have improved better than ever in my life (T3) and I'm generally feeling good and with energy, although I *really* have to stay on top of the potassium need or that mess everything up. Mfolate can be extremely difficult to handle for some. I'm one of those. So it took me nearly a year to work my way up to taking one full 400 dose. I would take a tiny amt and then stay at that level for at least 2 weeks, which is how long it takes, at a minimum, for me to adapt to. Then, move on, increase another tiny amt.
Taking potassium is scary at first, but food potassium doesn't do it. I always have a stack of bananas around and always have a 1/2 a one whenever I take potassium (powder mixed in 8 oz of water). Granted, we are all experimenting with our bodies. But most of us have no choice, or little choice.
BTW, with B-12 I was able to take it and work through the start-up symptoms over a period of months and never took potassium. With mfolate, it would have been almost impossible without potassium, and the need for it does NOT go away over time, although it appears to diminish some. I've only heard of one person who "didn't need it anymore" while taking mfolate. Others could get away with not taking potassium for a couple of days, but that's it.
Good luck!