Switching hamonica while playing

Hi David

Could you provide some instruction or is there any on your website on how to efficiently switch harmonica while playing with a mic?. For example I am working on a song where I want to switch between a low-c towards a c harmonica at some point in the song.  Is there any technique allowing to switch with a minimum of time loss? Sorry if my question is not clear, please let me know in that case. Thanks a lot. Joris, Belgium