Apple rolled out the first public beta of iOS 9.3.2 last night. iOS 9.3.2 is largely expected to be a maintenance release and not expected to include any new tentpole features such as Night Shift.
If your iOS device is already enrolled in the iOS 9 Public Beta program, you can download the over 1GB installer oner the air using the Software Update feature.
iOS 9.3.2 Public Beta 1 comes on the heals of iOS 9.3.1, which was released on March 31, and iOS 9.3, which was released on March 21.