Its a bit hard to follow why the BFO analysis from the 1839 satellite call changes things now. They presumably had this information before. But the media release certainly suggests this data is being used to refine the most likely search area.
Anyway if we accept the location of the last primary contact at 1822, this fits pretty well with the first "ring" at 1825. Unlikely the plane turned south between 1822 and 1825 as this would have taken it over land.
Then a turn to the south by 1840 - not long after passing the "tip" of Sumatra.
Its hard to identify a constant course that would hit all the rings at the right time. Best fit appears to be close to due south - although the distance covered between the 2141 and 2241 rings seems a bit large.
Assuming the last ring = fuel exhaustion and crash, we know the plane flew for a defined time from last known point. We can estimate an interval of most likely speeds from the fuel load and fuel consumption. So we can estimate an interval of most likely distance covered from last known point. An earlier turn south doesn't change the known duration, nor the estimated velocity or distance covered. These stay constant.
So an earlier turn south presumably puts the crash a bit further south west along the 7th arc.