Congrats! lovely ring
Congrats! Start planning whenever you want. Typically you want to book the major items (venue, caterer, etc.) about a year in advance, but it's not always necessary.
We got engaged in December and didn't even really start seriously talking about plans until around May or June. It was nice having time to enjoy being engaged and narrowing down theoretical plans before jumping into the stress of actively planning. We booked major stuff in July. We got married the following June. My sister got engaged and within 3 days she had EVERYTHING booked and bought her dress the following week. She had an 8 month engagement. She also had been the type that had imagined her dream wedding since childhood and already had a Pinterest page filled with wedding ideas. She knew what she wanted and immediately jumped on making it happen. So, it depends on how much time you have before ideal wedding date and how excited and anxious you are to jump into planning.
So, if you are thinking August 2016, you have plenty of time. If you have a venue or certain vendors you already know you want, book those early to ensure you get them. But, otherwise, if you don't have particular vendors you NEED to have or if you are flexible on the date, then you can wait to book those things until summer.