Eating Celery everyday or every night is perfectly fine and will provide you with the needed nutrients your body requires to stay healthy.
Another surprising benefit of Celery is that it can sometimes cure Insomnia and help you sleep so if you're having trouble falling asleep then try eating some celery every night and see if it helps you fall asleep.
I love eating celery as a snack in the evening and I tend to sleep better as a result of eating the celery.