For an insurance surgery covered by BCBSIL can my surgeon require a deposit to schedule the surgery?

To schedule my surgery the practice is asking for a $500 deposit to hold a date on the schedule for my surgery.

I am told that it is a refundable deposit that I will get back on the day of surgery as long as I don't cancel with less than 7 days until surgery

Is this allowed under a BCBSIL plan?