Since the evolution of 
can be written: (t) = 1.0 - (1.0 - o)/(v/vo)2), then it is clear that a decelerating expansion drives towards 1.00 (left) while accelerating expansion drives away from 1.00 (right).
For a pure matter model (deceleration, with v/v0 
a-1/3) we see the evolution of (a) for six models with values of (CMB) of 10%, 1% and 0.1% above and below 1.00. For those above 1.00, the divergence of corresponds to turnaround, followed by collapse, while for those below 1.00 the approach to zero signifies constant, coasting, expansion.
Notice that for o (today) within the range 0.95 - 1.05, then at the time of the CMB we need to be within 0.9999 and 1.0001 (curve would be the next one in the series).
Figure from Whittle's Teaching Company Course, and upcoming undergraduate text.