not to panic you or anything but you probably need to start dress shopping pretty soon as some dresses take 8 months to get in and then you will need to alter them.
I would go out and try them on and get some ideas. plus you can start talking with the sales associates and shop owners to see how long it will take to get a specific dress in.
not sure when you should start talking with a florist (if you need one) but I know that where I'm from they only do a certain number of weddings a weekend and sometimes the good ones book up fast. you may need to start thinking about that. The same goes with the cake unless its funished by the reception hall.
Seconds on the dress, although most designers really only take 4 mos to come in. My dress was ordered in December and my wedding is in May. But I have completely changed the idea of what I wanted based on my dress, especially since my dress has color. So get out there and see what you like and then you can also find out dates to trunk shows too. HTH!
i agree with everyone else on this one, the sooner you find your dress, the better you will feel about everything else.
as for everything else, bridal magazines are a wonderful thing. get as many as you can. tare out any pics if you see anything you like because it is way easier to find what you want if you have a pic. i kept a note book with those clear sleeves with tons of pics in it. i tore pics out of any magazines i could get my hands on. and kept a disposable camera in my purse to take pics of wedding dresses as i tried them on and took pics of everything i saw that resembled what i wanted. i really don't want to make you nervous, but these are just things that kept me on track so i didn't get worried about things not working out the way they are supposed to. i also took pics of the things that i ordered so that i could keep track of how things were looking.
one last word of advise. i would go to a book store and get a wedding planning guide. just so you have a guide on terminology, and a place to keep everything organized. i had a book that had a place to write down everything from guest list to where what hotels people were staying in, to when and where things were being delivered. it was a life saver. and it had explanations for everything anyone could possibly say to you reguarding weddings.