|Is it too late in the year to till leaves into the garden?|
|No, as soon as the soil is dry enough, you can work leaves into the garden. You can tell the soil is ready by taking a handful of soil and squeezing it very hard. If it crumbles when you open your hand it's ready. If it stays in a ball...let it dry out some more!
The leaves will decompose more quickly if they are shredded. If they are fairly dry you can shred them by running the lawn mower over them a few times.
If possible, wait a few weeks after adding the leaves to do your planting.
The other alternative is to put them into your compost bin. They'll work VERY well there!