30yo, i've set aside 20k in FD for emergency funds. Is this amount too big? I don't have kids, don't have high expenses. Am wondering if this amount is too much?

If this $20k makes you sleep peacefully at night, why not? Everyone's comfort level is different. You can start channeling whatever money you save now into investing. Not every dollar needs to be optimised.

Think it might be too high. Just set it to 6 months of your expenses

How far ahead do you think this emergency is gonna happen would determine the horizon of FD I guess.

You should not place emergency funds into FD, as they are not liquid enough when you need the cash.