calendar availability

You're going to get lots of opinions on this. Ultimately it's up to you, and your decision is based on your market and your experience level.

My market is highly seasonal and has a very short booking window. I could probably set a 3-month window and do just as well as if I had a 12-month window. I don't even want people booking 10 or 12 months out. They're extremely likely to cancel. But that's because I'm in a a regional drive-to beach town, and my typical stay is 3 nights. 

Whereas if you're in a fly-to destination, very high demand and limited supply, and if you prefer to book entire weeks at a time, then you're asking people to plan much further ahead, and you will want to give them a wider booking window to allow them to do that.

You didn't mention your experience level, but that plays into account as well. If you're an expert in your area and you know you're pricing cold, meaning you know what you're worth, then you can afford a wider window. But if you're relatively new, or still learning your market, or still trying to figure out your pricing, then you want to keep your window short. Otherwise your whole calendar will fill up with cheap stays.

My property is in downtown Atlanta close to the stadium