afni.nimh.nih.gov

Looks like you are on the cusp of runability: you need 9 time points.

I am not sure what correlation values of so few time points would mean. The stdev of a Pearson correlation value scales with 1/\sqrt(N-2), so for N=8, that would be 1/sqrt(6) ~ 0.4, which is preeeettty huge, consideration the Pearson r range is [-1, 1]. That means that your estimates with so few time points would be dominated by noise.

--pt