Sleep training for naps

How long do you try to get a 6 month old down for a nap before you just give up and let them stay awake? We’re going on 35 minutes so far and she just will not go to sleep 😩

I’m worried I’m going to be spending more time trying to get her to sleep than she will actually stay asleep for 🤦🏻‍♀️

I know she’s tired because she’s been awake for 3.5 hours and she’s yawning and rubbing her eyes like crazy which are her signs that she’s tired. 😴