How long until I put my canary back in my room after burning scented candles?

I cannot give you an exact timeline, but so long as the room is well ventilated your bird should be safe after an hour. Think about it this way - if you can no longer smell the scent in the room that likely means that the chemicals have dissipated.

Remember that not only candles and incense can be dangerous to birds, teflon (the coating that many non-stick cooking items have on them) can also be very deadly to birds, especially if they reach a high heat.

Good for you for understanding the danger of chemicals in the air and caring about your birds health!

I'm guessing they're unsafe,cause they're drawn to the scent, the burn themselves. So as long as they're out your're probably ok.