When should Obama start running ads showing McCain as a flip flopping machine?

I am really looking forward to those ads. McCain has flip flopped on everything under the sun and is the furthest thing from a "straight talker". General Clark said it best "We don't know which John McCain we are going to get." He is all over the place on the war, abortion, taxes, the religious right, whether the war was going to be easy or not, off shore drilling, and on and on and on and on and on....

So when do those ads start running? Now or wait till later?

And Obama should box him in during the debates by arguing for or against McCain's earlier stances, then when McCain says "That is not my stance on that issue", Obama can say: "That was your first stance as you stated in July of 2003....." Obama could create a theme in the debates that focuses on all the different stances McCain has taken on the issues over the years, then as Clark put it say "Which McCain are we going to get?"

I think that was the main issue that sunk Kerry, (thanks repuke smear machine for the idea;) )