Marvel just officially confirmed that Ant Man is set before IW:
From the Marvel Cinematic Universe comes "Ant Man and The Wasp,"a new chapter featuring heroes with the astonishing ability to shrink. In the aftermath of "Captain America: Civil War," Scott Lang grapples with the consequences of his choices as both a Super Hero and a father. As he struggles to rebalance his home life with his responsibilities as Ant-Man, he's confronted by Hope van Dyne and Dr. Hank Pym with an urgent new mission. Scott must once again put on the suit and learn to fight alongside The Wasp as the team works together to uncover secrets from the past.
They are gonna need to handle this just right because the idea of having to wait for Part 2 already kinda has me pissed off.