As a makeup artist, I freelanced many weddings, and I can tell you that glow can easily be created with product.
If you go vegan, that's great, you'll fit into your dress, but it may or may not impact your face...stress may wear you out and have your hormones jumping a week before your wedding negating everything. Also 6 months in advance if you really didn't want to do it may have you binging on bad things before your event.
Find a great makeup artist, and start cleansing inside and out 1 month to 3 weeks before your wedding date.
Masks to detox your face should be done weeks in advance to alleviate allergic reactions or adverse effects.
Detoxing your insides and proper nutrition at this time will make you glow as well...