That sounds about right. We're doing Dec 1st for a Dec 27th, pretty much the same timeline as you.
i think it depends on when you need final counts/menu decisions...which also determines your final cost...and be sure to give yourself and your FI enough time to call on all those you don't receive RSVP's from...
no i don't think that is too late at all, if anything i'd say it's early.
i've heard your rsvp should be 2-3 weeks prior to the wedding depending on when you get the invites out. i.e. if you get them out 8 weeks in advance set the date as 3 weeks prior, if you get them out with 6 six weeks out, 2 weeks prior. and you are fine getting them out this week, that's 6 weeks prior so don't stress.
i guess it depends on when you need to let your caterer know by, but if that's not an issue then I'd say set the date for August 16.
my wedding is sept. 6 and i'm setting my rsvp date for aug. 20, hopefully getting them out today!
i'm putting mine a full month before the wedding, because we have to release any unsigned hotel rooms 2-3 weeks in advance.