How many language lessons should I be booking?

There's no right or wrong answer here.

One thing we want to emphasize is that consistency is 10x more important than frequency. Students that take lessons consistently 2-3x per week have much faster and more effective results than students that jump into the deep end by booking lessons 5x the first week, then 1x the next, and so forth.

Consistency > Frequency. Take small steps and build on it.