"DJI has released a new GPS module for the A2 flight control system. This new module, called the A2 GPS PRO PLUS, offers a significant performance upgrade over the current A2 GPS PRO. Read on for details on this new system and the tests DJI performed to verify the performance of this new module." http://www.dji.com/info/releases/introducing-the-new-a2-gps-pro-plus-module
Only when the IMU fails and you will need to allow some time for it to ascend to the required altitude. Andy.