I say it depends on where your guests are coming from. I sent my STD's out at 9 months before because I have a lot of family from out of town as well as I have a lot of family that takes vacations around my wedding date so I wanted to make sure they knew about the wedding date before making vacation plans!
6-8 months is the typical time frame. We're getting married next March and are sending out save the dates in August! Starting in July we'll be taking them to any family events we go to and give them to family so that we can save a little bit on postage
6-8 months is considered acceptable, however if you have guests that would be coming from far away or it's a major holiday weekend (it looks like you avoided Memorial Day, so you should be okay on that aspect) you might consider sending them out on the earlier end of the time frame so guests have adequate time to make travel arrangements.
It's usually 6-8mo. But if it's destination I would do about 10. Looks like it's the weekend after Memorial Day so some people may want to know just in case they can't afford to travel 2x. Ours is on Memorial Day weekend so we opted for about 9 mo ahead.
Depends on how many out of town guests you have. Ours is a destination wedding and we sent save the dates out 6 months in advance. We probably should have sent them out at about 10 months, but we didn't have the date or location nailed down.