The lesson sequence is a reference, not a requirement. Let interest and development-level be your primary guide.
Progression
The lesson sequence guide shows the progression within each lesson category vertically, with beginning lessons toward the top.
Lessons aligned horizontally can be introduced to the same age group, but don’t need to be introduced simultaneously. They can be though!
Where a lesson falls vertically indicates when a lesson can be introduced, but it could also be introduced later. There are things to be gained from each lesson category at every age!
Some common core standards indicate children learning certain concepts later or earlier. See Learn Libre’s NGSS alignment for more information.