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This is Dr. Christian. I'd like to help. Is she otherwise acting normal (eating, drinking, active, etc.)? Has she passed any urine since the stone?
As long as she is not trying to urinate but can't and doing well otherwise then it is fine to wait until morning. If she tries to urinate but can't pass anything or starts vomiting then take her tonight since that could be signs of a urinary blockage. Luckily that is extremely rare in female dogs. If you have more questions please reply back. Make sure to save the stone and take it to your vet tomorrow. They may want to send it off for testing to find out what kind of stone it is.
You're welcome. Good luck.