Absolutely! We have taken a "booking fee" usually about a third of the full package price to book the day and then the rest of the fee is paid 30 days before. We have never, in nearly ten years, been questioned about this or had a problem with it. We do, of course, also insist on a signed contract. I think any bride/couple who argue with this or try to negotiate over it are going to be far to much trouble and not worth working with!!
I ask for 30% at signing or 3 day of singing. I then ask for the remainder 14 day prior to event. I also let the client know that if they cancel the event with in 45 day 50% of the remaining balance is due. Th3 30% is non Refundable Retainer. I do allow payments after the deposit if needed.