If you are having a traditional engagement party, an engagement party toast to the happy couple will usually occur. Engagement party toasts are usually given by the father of the bride, however in his absense anyone can give it, usually a close family member on either side. It is usually given after all the guests have arrived, roughly an hour into the party.
The guests will all be asked to raise their glasses, the bride and the groom should not. Traditionally after the toast everyone drinks but the bride and groom. However, these days some brides and grooms do a small clink of their glasses and have a sip of the beverage, usually wine or champagne.
After the toast is completed, the bride and groom should say a few words. This will include thanking the person who gave the toast, thanking the host or hostess of the party and thanking everyone for attending.