Find the Right Florist!
Whether you have an idea of what you want or you are going into the flower decision completely blind, it is a good idea to consult a professional to help conceptualize your wedding day vision.
As with any portion of your wedding planning, if you can start early, you definitely should! The benefit being that, if you have at least a year before the wedding day, you can take a look at the seasonal flowers that will be available to you at that time of year. You may even be able to get a sample bouquet made with your preferred seasonal flowers at this time. The details and specifics can be discussed as you get closer to the big day, typically a few months before the wedding.
On average, you should expect to set aside 6% of your wedding budget for flowers - maybe more or less depending on your taste, style, and budget. The florist will be able to guide you in choosing items and designs that will work with your budget.
Before meeting with potential florists, gather as much inspiration as possible - including styles you like as well as those you dislike. If possible, collect photos, color swatches of linens and bridesmaid dresses, invitations, etc. to bring to the meeting. This information will be a great starting point and will, hopefully, convey the theme and vision you have for the wedding day.
While at the meeting, it is also very important to review the florist's work on previous weddings so you can get a sense of his/her style and how he/she conducts business. Once you have given the florist your basic idea and preferences, he /she can prepare a proposal so you can get a better feel for pricing and how it works with your budget. If you feel comfortable working with this person or company and the proposal fits within your budget, then you have your florist!