  We revisit the precessing black hole binary model, a candidate to explain the
bizarre quasi-periodic optical flares in OJ-287's light curve, from first
principles. We deviate from existing work in three significant ways: 1)
Including crucial aspects of relativistic dynamics related to the accretion
disc's gravitational moments. 2) Adopting a model-agnostic prescription for the
disc's density and scale height. 3) Using monte-carlo Markhov-chain methods to
recover reliable system parameters and uncertainties. We showcase our model's
predictive power by timing the 2019 Eddington flare within 40 hr of the
observed epoch, exclusively using data available prior to it. Additionally, we
obtain a novel direct measurement of OJ-287's disc mass and quadrupole moment
exclusively from the optical flare timings. Our improved methodology can
uncover previously unstated correlations in the parameter posteriors and
patterns in the flare timing uncertainties. According to the model, the 26th
optical flare is expected to occur on the 21st of August 2023 $\pm$ 32 days,
shifted by approximately a year with respect to previous expectations.
