Do I take pods off the stalk when they are green or wait for them to split or turn brown? Thank you

to NGA.

Do you want to grow new litle Yuccas from seed? If so, wait for the pods to split. If you aren't hoping for seeds, you can take them off anytime you want.

What's the goal?
If you are planning to have a dried arrangement, picking green would probably be attractive.
If you are trying to collect seed, you should probably wait for the seeds to mature... This means the pods split open on their own.
If you just want more plants.... There's really no need to collect seed.. they spread like wildfire from the tubers. Just dig some off-sets.