The update size is around 17mb so downloading it via air would not take that long or if you want to download manually here are the instructions.
- Download the update from here (Google official – d323ca384aaa.signed-passion-GRK39F-from-GRJ22.d323ca38.zip).
- Rename the file to update.zip. Note that if you’re using Windows, just rename it to “update” (no quotes, of course) because it’s already a zipped file.
- Copy the update.zip file onto your microSD card.
- With your Nexus One off, hold down the trackball and press the power button.
- You’ll be booted into a white screen with three Android robots on skateboards. Select “Bootloader.”
- On the next screen, select “Recovery.”
- Your phone will reboot, giving you a picture of the Android robot and an exclamation point inside a triangle.
- Now press the power button and volume up button at the same time. It could take a couple of tries.
- Now (using the trackball this time) choose “Apply sdcard:update.zip” and let things run their course.
- Reboot and enjoy
Credit: Android Central