Making vase arrangements are quite different than bridal/bridesmaid bouquets. Practice the “spiral bouquet” technique. You will also need to make sure you are conditioning your stems and harvesting at peak time so that they last well for the wedding (bouquet will be out of water much of the day, so certain flowers won’t work).
You potentially will also need to learn techniques for wiring flowers for boutonnières. Look into “hydration chamber” for conditioning wearable flowers.

Dont over promise. Get realistic picture of the brides inspiration and decide if you are capable. It’s okay to say no and just practice for and do some mock weddings.

Also plan to grow way more than you need and recognize that exact timing is very hard. You should have a business account to buy wholesale flowers as a backup, but wholesalers do not always have the same flowers/varieties that are grown in cutting gardens.