I beat the game unless you count the little graffitis and horseshoes and ****. It was a good ride, but far from the best game ever.
Here is a map I've pulled up in case you don't know where the mission can be found:
For either of these spots, I've read you do have to be there at a certain time of day on certain days of the week. I was lucky in stumbling across it at the right time, but not with that damn Millie. When I was waiting to date her, it took weeks to get the red marker outside her house. I actually ended up using the time acceleration cheat; maybe you'll give that a shot if you feel like you're waiting too long for the marker.