Both my kids are now in drivers permit territory. (aaah-I KNOW — how did this happen??)
This makes me think of earlier milestones. How do you know when your kid is ready to first eat solids? Sleep in a big kid bed? Start potty training? You read the guidebooks, you tune in to your child, and you watch for signs. You give the transition a try and adjust to and fro.
Unlike these previous examples, learning to drive is a legal thing that is tied to age first and readiness second. In our state (Colorado) a teenager can take a written test through the DMV at age 15 and begin a year of practice driving.
My husband and I find ourselves doing a curious thing in anticipation/preparation: