I would not buy a dress until you know for sure what time of the year you will have it. Since we became engaged we have looked at July, October, November and December. We considered the Mountains, Europe, a Southern plantation, the beach and finally settled on Disney all in a relatively short time. We have gone back and forth between informal beach receptions, nicer indoor receptions or dinner at a restaurant. All the different options made me consider a different dress. Since you will want your venue decided upon preferably a year in advance that is when I would want to look for a dress. You will know if it will be outdoor casual, formal or indoor casual or formal; if it is a midmorning casual affair, or a formal evening event. There are so many different combinations! What I did years ago before I was engaged, was my friends and I had wedding portfolios. We looked at dresses and decided which style we liked best on us, then we moved to other items. The Knot is great for that stuff! It is a good idea to have ideas narrowed down for sure, but I would wait to buy the dress, but by all means go try some on!