Don't worry about flu season if you are breastfeeding, your baby will get your anti-bodies. Myself, DH and dd1 all got an awful D&V bug and dd2 was 3 weeks at the time and she was fine!
I tried a bottle at 3 weeks and that was too late- she refused it. So if you really want to give a bottle, introduce it sooner so baby is used to it. Your milk supply will be big in the first week or 2 so you could pump loads then and freeze it in bags for the wedding (I bought freezer bags from amazon)
Don't stress too much about it- who ever is looking after your baby could also have some formula just in case- to put your mind at ease too.