Google Navigation App - beginning of each voice announcement cut off

[AC Question]

I have just bought a new Android smartphone (a Vodafone Smart Ultra 6). I have today tried for the first time using the Google Navigation app. In general it worked very well, but the first few words of each announcement were lost. I guess this is because my bluetooth headset (which can be paired with several sound sources) takes a while to switch to the bluetooth source, and this is enough to cut off the first few words of the announcement. One solution would be to have an adjustable delay after enabling the Google Navigation app to transmit sound via bluetooth, but before the beginning of the voice message.

Could this be done?

Is there any other solution to this problem, which makes the Google Navigation app much less usable than it should/could be.

Thanks - Rowan