Your wedding is one of the biggest days of your life. It is the one day when all eyes will be on you. That is just one of the reasons that you want to look your best, but it is not just about looks. You want to feel great and you want the first day of this part of your journey to set the tone for how you live your life in the future. You might set your fitness goals with your dress in mind, but afterwards, you need to be able to maintain them. Target specific areas, but understand how those areas affect the rest of your body.
The core is the best place to start because everything radiates out from that. Also, it is hard to work the core without inadvertently working other areas of the body. Most of the core workouts also place a lot of focus on breathing, so these workouts can double as tension relievers and ways to hone your focus.
Your arms and legs are likely to be exposed at least a bit, so you want to firm them up before the wedding. You can work these areas when you work your core. However, it pays to focus on these areas on their own as well. Any additional movements you make beyond your daily routine is going to help sculpt your muscles. In order to get even more out of your movements, consider adding weights or resistance bands.