"Save the Lester Missions for after you beat the game that way if your smart and save most of you money during the story mode you can put a crazy amount of money into the stocks and get a massive return profit when you sell them."
Are you sure you can do this? I was going to do it this way, after reading the tip online, but I don't have any missions I can go to except a "B?" icon for michael or franklin, and the L for Franklin. I may have a few other regular "?" missions for Michael and Franklin. I'm on the 3rd heist (after the yellow submarine/cargo ship heist) and have collected everything that needs to be done (getaway car, garbage truck, masks, etc). I did all those with Trevor and he has nothing on his map except Cletus and a couple ? locations.
While doing those I got a message from Franklin saying he couldn't do the heist he had to talk to Lester first. If I go to Lester is it going to force me to do the first assassination, or is there something else you meet with Lester about? If not, it seems I may have to do an assassination before continuing with the heists/story line.