Planning for wedding flowers and floral arrangements should begin several months in advance and you should have initial contact with your florist at least one month prior to your wedding.

If you require a large number of arrangements or elaborate designs, your florist may need to start preparation a full week before the wedding. Color-matched ribbons and unique flowers as well as other floral accessories can take time for the florist to special order – often a week (sometimes longer).

If you feel overwhelmed at your first visit, remember, flowers, weddding bouquets and arrangements are the florist’s specialty.
Your florist will be able to offer suggestions and provide you with examples of his or her previous work with flowers, styles, color coordination, accessories and decorations.

When you visit your florist, take a picture of your dress, your bridesmaids’ dresses and your groom’s clothing. Also take swatches of fabrics including your gown (unless it’s pure white) and any pictures from magazines of wedding bouquets, bridal bouquets or wedding flowers that are appealing to you.

Reference: link2love.com