Swedish tech site SweClockers claims NVIDIA plans to reveal its new Pascal architecture at Computex 2016 (May 31 - June 4). This will likely be a paperlaunch but NVIDIA intends on getting its GeForce 1000 (if it will be called that) series out of the door by mid-June.
Since we already know that AMD is planning its Radeon M400 series in April, NVIDIA has no choice but to deliver GeForce 1000M series in similar timeframe. Notebook manufacturers can therefore refresh their whole portfolio with new laptops based on next-gen (and last-gen) graphics cards from both vendors.
It is very unlikely NVIDIA is planning to talk about the Big Pascal (GP100)-based products. Computex launch would probably focus on GM204 successor, the GP104 and possibly GP106.