That is often a different type of difficulties. I was thinking about decision like, should I buy car A or car B. I've done my research. Economy, safety, et c. are very similar. But it is a lot of money, and I don't know which is the "best", and of course I want the "best". I could spend weeks on a decision like this. Now I just acknowledge that they seem to be equal. Car B comes in a nice shade of red that I really like, so I buy car B.

Regarding your question, there's always going to be known and unknown unknowns down the line. My only advice in that case is to get to the unknowns as fast as possible. And from the start take into account that you most likely will have to rebuild a big part when you learn more. That is one of the reasons modularity and decoupling is so important. You want to be able to easily scrap and replace one part without it affecting everything. And keep it simple. Never try to build something that should be capable to handle all imaginable scenarios in the future. You'll be bitten by one of the unimaginable ones, and your complex "can handle everything" architecture will be too rigid to change.