Start at the recommended DIN and figure it out yourself from there. How do you expect anyone else to help you out?
The FKS binding does have more uncertainty in its adjustment. Like the forward pressure gauge is very rudimentary compared to more modern bindings that have very clear gauges. You basically will just have to learn to get a feel for it.
Your din setting is something you are going to have to figure out for yourself. It tells you how easily you are going to come out of a ski, but nothing about how easily you want to come out of your ski.
On my mogul ski, my din is set much higher than recommended, because I feel safer with a lower chance of pre-release in exchange for a higher chance of them staying on in a fall. On my park ski, my din is basically at recommended, because it's much lower impact and I am more likely to fall in a bunch of different ways.
You have to decide what your priorities are. Don't ask others to do it for you. The recommended DIN was designed to be the best option for 95% of skiers, and is the only thing that other people should advise to you.