Congratulations!
The farther ahead you plan everything, the more likely it is to get done the way you'd like, and the more time you have to correct anything that goes wrong.
Have the bridesmaids order their dresses, shoes, and accessories now.
Your daughter should arrange her final dress fitting WELL in advance... like several months in advance.
Check with the officiant that the wedding dress and bridesmaids' dresses are acceptable. In some churches, the bride can't have her shoulders bare (so no strapless or sleeveless dresses) or have too short a skirt. They may or may not be more lax with the bridesmaids.
Organization is key. A former coworker of mine actually put together a Gantt chart, with herself, her fiance, parents, in-laws, and wedding party members as resources... she had task lists, dependencies, etc.
Something you may not want to hear, is that your daughter and her fiance are in charge. You're not. If she wants her bridesmaids to carry bright pink and orange flowers, and you know that will clash horribly with their red dresses, certainly you can advise her to rethink her choice, but ultimately it's her choice. (Although I'm sure she has better taste than that!
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Also, something WILL go wrong on the wedding day. With that many factors, something is bound to happen. Hopefully it will be something minor, but brides (and moms!) have a way of stressing out over every little detail, e.g. "I LOST A BOBBY PIN! OMG IT'S THE END OF THE WORLD!!" (yes I've seen a bride do this). The important thing to remember is that, the photographer may have been late, the band may have forgotten that the maid of honor wanted to give a toast (happened at my wedding), the guests may have been stuck in traffic between the wedding and the reception... at the end of the day, they're just as married.
Good luck with all the wedding planning.