Shouldn't we have something that doesn't seem to piggyback on the existing celebration, and that people will recognize as a unique thing and not confuse with the Gay Pride events?
It's not a single day but usually a whole week -- Pride Week. It is in late June because that is when the Stonewall Riots were in 1969.
Around here the rainbow colors are very definitely a gay pride thing. All the gay bars have rainbow neon signs, etc.
I wouldn't mind the colors being for APD as well, if you hadn't scheduled APD for right around the time of Pride Week -- it's the combination of the two that will cause confusion. No one is going to ask me about Autistic Pride if I wear a rainbow t-shirt with "Autistic Pride" on it at that time of year -- they will assume it's for Gay Pride Week, and if anything, they'll probably think it's for Autistic Gay Pride. 
Pride Week is a pretty big deal in many cities -- parades, festivals, etc. So it is a shame that the APD will likely be overlooked because of this.
Anyway, I support what you are doing, I just thought it was odd that it was scheduled when it was, and thought I should mention it if no one else had.
More like the end, or the third week -- for example, it's June 19th - June 26th this year. (See http://www.hopinc.org/home/.)
I doubt most people who aren't in one or both of the groups will notice the difference.
Indeed it is... I guess I am just bummed that the APD won't get the attention it deserves... if you live where Pride Week isn't in June, it will not be an issue for you, but here in North America, at least, it's sort of the equivalent of deciding to have Labor Day on Christmas or something -- one event will always be overshadowed by the previously existing one. 
Anyway, thanks for taking this on, and I hope you do well with it.
- It explains autism as normal and positive part of human diversity.
- It is the only non-medical model auf autism I know of.
- It is part of a general theory of all humans.
- It explains recent research.
- It explains the diagnostic criteria for autism in DSMIV and ICD-10
- It explains personal experiences of individuals with autism.
- It iss written by people on the autisitc spectrum.
Here it is: http://www.autismandcomputing.org.uk/attention.pdf