Hi There, I can answer you from my experience... I'm using my coach since like 2 month now and at the begining it was kind of what you are describing... instead of walk I always was "forcing" myself to trot very slowly...
Now I notice my heart is adapting much faster to the zones... before was taking me more than a minute and now is taking me up to 10 sec to slow down from yellow to green or blue.
I guess the -very unfit- condition will make it a little worst.
I was overweight for about 10 kilos... I loss about 3 kilos in this 2 month but my heart condition looks much better even if I have a relatively high heart rate yet...
What I have done to have a peace in mind
was to go to a sport doctor... I had some test done while running and I set up my zone with the help of the doc.
My average page is around 6km/h, my rest zone is about 85 and my red zone is set in 182. (I'm 33 and about 83kg now)
Hope it helps!
