Off-The-Wall Use For A Mad Magazine Cover #73521

This may be the oddest use of Mad Cover information yet...
I'm working on a memorial site for a hotel that recently closed its doors after over 40 years of service. I've been sent a photo of the Prime Minister of Canada and his wife (Pierre and Margaret Trudeau) visiting this hotel at some point in 1970s.
In the photo there's a kid holding an issue of Mad. Using your site (an incredibly well organized site, btw), I've figured out that it's issue #161, with a cover date of September, 1973.

My question: How far in advance of the cover date would an issue of Mad have been available for sale back then?
We're trying to date the picture to at least the right month, and we suspect it was June or July of that year.
Would it have been possible for a kid to have the September issue already in his hands in June or July, or would it be impossible for this to have been taken that early in the summer?

Thanks for your help,
Andrew Gurudata
Constellation Hotel Memorial Web Site

My Response:

It's very possible for July or August since Mad published eight issues a year at that time and always dated issues a month or two ahead of the actual release date.

Mystery boy with issue #161.