Seasons, at least, are entirely predictable. Plant growth is somewhat predictable. Travel times are mostly predictable (early trading). The timeline of children growing up is predictable if (big if) they survive. Livestock lifecycles were known. They knew how long various kinds of food took to spoil.

These are very important things and most of them take place on longer or much longer timescales than a few months. Early humans weren't monkeys, and after they had left the tropics, they couldn't survive without planning because getting food is difficult in winter.

You have to make those opportunities to plan long-term. Once you start to form those, it will be amazing how many opportunities present themselves.