How long does a magnetic pole reversal take to complete?
The entire process appears to take 3,000-4,000 years, according to Valet and Fournier's May 2016 review article "Deciphering records of geomagnetic reversals," which was published in AGU's Reviews of Geophysics.


  The complex dynamical structure of reversals is supported by
  sedimentary and volcanic records. Provided that resolution is
  adequate, the reversal process seems to incorporate one precursor and
  one rebound prior to and after the transition. However, the three
  phases are rarely observed in a single record. This is likely to be
  caused both by field geometry and recording limitations. The duration
  of each phase does not exceed 3–4 kyr. Therefore, precursors and
  rebounds can be seen as part of the whole process, and the expression
  of a continuum of behavior between secular variation, excursions, and
  reversals. Another possibility is that the dipole collapse is not
  large enough or that the nondipole/dipole ratio varies.


Better resolution of the process and the time involved will require at least a 10-fold improvement in paleomagnetic sampling resolution, the authors contend. And one of the challenges is finding suitable lava flows or sediment layers that were created during the transition(s) in question.

As for whether current fluctuations indicate the earth is about to have a reversal: We can't tell, because the recent paleomagnetic record includes similar changes (sometimes regional rather than global) that did not result in reversals, Valet and Fournier write.


  The present evolution falls within the normal range of field
  variability that prevailed for the past 2 Ma.