Phase Response & Bluetooth Devices

I have a question regarding BT devices and their phase/impulse response. I know that since in my case it's not possible to due a loopback (even acoustic), the response will be the entire system's response, and because there's no timing reference, REW puts the T=0 point at impulse peak. But what is the interpretation of the different responses and the impulse pre-ringing? My experience is that the phase & impulse responses change every time I do a pass, and I'm wondering why that's happening. Is the BT software going back in time for missing packets and stuff? Are any of these remotely audible? Is there a way to isolate the acoustic phase response for BT devices?

Is there a way to avoid this and get a consistent phase response? Currently I'm using a BT USB dongle to connect the device to REW through Java. Would using a different BT receiver change anything? Or using Asio4all?

Thanks in advance