Yes, you'll deposit the check in an account (this is a great time to open a joint account in both of your names to change later) and you will not use any of that money until after the wedding. Send a thank you note right away to let your guest know you received their generous gift. Remember to write a personal note inside the card; don't just send a preprinted card with your signature as many do.
Best Wishes, Top Wedding Questions Forum Moderator - "Write your sorrows in the sand, your blessings in stone".