The T2K experiment has provided the first hint for the best-fit value for the leptonic CP phase delta(CP) similar to -90 degrees from neutrino data. This is now corroborated by the NO nu A neutrino runs. We study the implications for neutrino mass hierarchy and octant of theta(23) in the context of this data assuming that the true value of delta(CP) in nature is -90 degrees. Based on simple arguments on degeneracies in the probabilities, we show that a clear signal of delta(CP) = -90 degrees coming from T2K neutrino (antineutrino) data is only possible if the true hierarchy is normal and the true octant is higher (lower). Thus, if the T2K neutrino and antineutrino data are fitted separately and both give the true value of delta(CP) = -90 degrees, this will imply that nature has chosen the true hierarchy to be normal and theta(23) approximate to 45 degrees. However, we find that the combined fit of neutrino and antineutrino data will still point to true hierarchy as normal but the octant of theta(23) will remain undetermined. We do our analysis for both, the current projected exposure (7.8 x 10(21) pot) and planned extended exposure (20 x 10(21) pot). We also present the CP discovery potential of T2K emphasizing on the role of antineutrinos. We find that one of the main contributions of the antineutrino data is to remove the degenerate solutions with the wrong octant. Thus, the antineutrino run plays a more significant role for those hierarchy-octant combinations for which this degeneracy is present. If this degeneracy is absent, then only neutrino run gives a better result for fixed theta(13). However, if we marginalize over theta(13) then, sensitivity corresponding to mixed run can be better than pure neutrino run.