When to try on wedding dresses

Getting married next January and I'm not sure when I should start to look at dresses. Currently losing weight. I want to be about 170's/ 160 when I try it on. Rn I'm in the 180's but I've started to go to the gym more consistently and also getting stricter with my diet. Obviously I can fix the dress as the date come closer and I lose more weight. Just don't know on average how in advance I should order one.