First of all, maybe start giving a bottle of EBM on occasion, maybe once every day or 2, a few months before the wedding, so baby doesn't straight out refuse it if thats what ends up happening. He/she will be used to a bottle. But wait til BFing is well established
2nd, don't rely on your others age for teething. My DD1 was 7 months when she got her first tooth, DD2 was 5 months. DS closer to 8 months. They are all different
Good luck & if your dress is too big you can have it taken in. If its too small, its harder to take it out