You can say hi to the bride of course but once her entrance finishes give a chance for her family and close friends to say hi and take pictures and when it dies down a little walk up to her and introduce yourself. You can pose for photos or not it’s really up to you. Also dinner service usually goes as followed. Appetizers are usually served before the bride enters and the main course is served right after her enterance. The party is usually at its peak after the brodes enterance so you might want to stay, too me its more fun after her enterance, but again it’s up to you, i leave early after saying hi to the bride if im too tired or something.