[nomel]

I don't think it's a good idea to start the implementation firmly planted in the trees of the forest you're trying to see.

I think it's best to start with something like an outline. This could be comments, tests, sparse pseudo-code, or some level of documentation that explains what you're trying to do.

Once you have a rough idea of the pieces that are required and will roughly fit together, understanding the consequences of the decisions you make while implementing those pieces will come more naturally, and can help prevent rework. Most architecture mistakes, and often bugs, are from not understanding the consequences, which isn't really possible without having the mental model.