Not exact dates of toys on shelves but something to get you or others started on further research (but if the TFwiki guys haven't found it...). That the comic might have been out first is something I've come across elsewhere. Finding a date for the first TV ads would be next to impossible.

February - Hasbro Bradley unveils their new Transformers toyline at Toy Fair.
March - Marvel Age #17 announces the April debut of the Transformers comic book.
Spring - The first animated commercial advertising the Marvel comics airs on US TV.
May 8 - Issue one of the Marvel comic is released.
May 22 - The first Usenet post about Transformers is posted by Ted Nolan to net.comics. In a prediction of things to come, it is mostly complaints.
Spring - Transformers toys start filtering into stores across the United States.
September 17 - "More than Meets the Eye, Part 1" premieres on U.S. television Saturday morning.
http://tfwiki.net/wiki/Transformers_timeline#1984