Before the interwebs, how did you know a game was coming? I'll answer for you. You read magazines. The first blurb you read about GT2 kept you glued to mag rack, right? Then when the PS3 was approaching store shelves, you were glued once again for GT3 info. When there were write ups in every mag, you probably bought it, I know I did. When the games came, you bought them, just as I did. GT4 came out at a time when there were established interweb users. Which means you no longer depended on mags to give you info.
What's my point? You did not find out about the upcoming GT game in "advertisments" on radio and TV. You found out through articles containing information. Right around when the games were about to release, you started seeing commercials.
Again, airing commercials for games 4 months before they come out is a waste of millions of advertising dollars. That's what magazines and the internet is for.....free advertising and promotion of your product. Aka: industry buzz.
Now, what point were you trying to make about them needing to start advertising 4 months before a game's release?
Name 1 game that you see advertising RIGHT NOW that will be out in 4 months. How about this, 2 months? Better yet, surely you can name an ad for a game coming out in 1 month (30 days), not Aug. 4th.
Trust me, this is not the only place on the web that discusses Gran Turismo. Get your head out of the sand.