We analyze constraints on parameters characterizing the pre-inflating universe in an open inflation model with a present slightly open $Lambda$CDM universe. We employ an analytic model to show that for a broad class of inflation-generating effective
potentials, the simple requirement that some fraction of the observed dipole moment represents a pre-inflation isocurvature fluctuation allows one to set upper and lower limits on the magnitude and wavelength scale of pre-inflation fluctuations in the inflaton field, and the curvature of the pre-inflation universe, as a function of the fraction of the total initial energy density in the inflaton field as inflation begins. We estimate that if the pre-inflation contribution to the current CMB dipole is near the upper limit set by the {it Planck} Collaboration then the current constraints on $Lambda$CDM cosmological parameters allow for the possibility of a significantly open $Omega_{i} le 0.4$ pre-inflating universe for a broad range of the fraction of the total energy in the inflaton field at the onset of inflation. This limit to $Omega_{i}$ is even smaller if a larger dark-flow tilt is allowed.
