I don't know. Probably never, lol. At this rate we'll always have little ones in tow.
Legal age to stay alone in IL is 14. Now, I know lots of people do younger, but that's the legal age.
If just my oldest was with me, maybe 12? Around the time I'd be OK if I had to make use of the front seat.
At school pick up next year, I am thinking the big kids (8 and 9) can walk to ME. The van will be parked on a stretch of sidewalk and I'll pretty much always have the same spot. Far since I can't get there too early and sit with the littles. They don't have to cross any roads or drives. It is a long stretch of sidewalk and it gets cold, but the alternative is taking newborn, toddler, preschooler, and kindergarten child out on icy sidewalks that can never accommodate the stroller, near a road I can't trust littles to be safe around, to walk to them to meet the older kids, then back. I can't picture that at all. Seems best and safest if they walk to me.