How long would it take for a novel alelle to be fixated in a population?

Haldane's Dilemma is based upon the substitution cost introduced by J.B.S. Haldane in his classic 1957 paper "The Cost of Natural Selection" (Haldane, 1957). ReMine addresses these issues in his book "The Biotic Message" (ReMine, 1993).

Haldane's old model? — Haldane used a multiplicative-fitness model. (Moreover, for the parameters he used, it also approximates an additive-fitness model.) Both of those fitness models are still predominantly used today. Everything in "Haldane's model" is current with today's practice of evolutionary genetics (including Haldane's uses of fitness, fitness models, selection, alleles, genes, dominance, and Mendelian segregation). So if evolutionists throw-out "Haldane's model" they must also throw-out the modern textbooks on evolutionary genetics.Small selection coefficients? — Haldane assumed selection coefficients approaching zero. This gives the absolute minimum total-cost of substitution in each case. If you break Haldane's assumption, and invoke higher selection coefficients, then the cost increases, resulting in fewer substitutions, and Haldane's Dilemma worsens.The environmental-change scenario? — Haldane assumed substitutions begin in a peculiar way, via an environmental-change scenario. The scenario operates as follows. Neutral and slightly harmful mutations (though almost always eliminated outright) sometimes drift upwards in frequency, to arrive at moderate frequencies. Then, when the environment changes, one of these neutral or slightly harmful mutations is converted (it is alleged) into a beneficial mutation. This elevated starting frequency is where Haldane begins to tally the total-cost of the substitution. By giving the substitution a free head-start to an elevated frequency, it lowers the total cost of substitution. This cost-reduction is the only impact of the environmental-change scenario that Haldane allowed into his calculations. If you break Haldane's assumption, then it raises the total-cost of substitution, and worsens Haldane's Dilemma.1Constant population size? — Haldane assumed the population size remains constant throughout a given substitution (though he allowed large varieties of population size, each for a different substitution). That was done partly for mathematical simplification (in the era before computers were readily available to readers). When evolutionists break this assumption, they do not "solve" Haldane's Dilemma. They merely obscure it further. There is always a cost of substitution; it is unavoidable. It is not enough to merely object to Haldane's simplification. Evolutionists must actually s-o-l-v-e Haldane's Dilemma.Infinite population size? — Evolutionists sometimes claim Haldane assumed an unrealistic "infinite population size." That is untrue. If Haldane had done that, then the total-cost of substitution would always be infinite — when Haldane calculated its average value is 30. So Haldane obviously did not use an infinite population size. Rather, Haldane used something at the other end of the spectrum. To see it, take a haploid species, and suppose there are two independent alleles, A and B (at independently segregating loci), each with a frequency of one per thousand. By random mating, the genotype AB (containing both alleles, A and B) would have a frequency of one per million. But if the population size is only one thousand individuals, then in a given generation, genotype AB cannot actually exist at a frequency of one in a million. Instead, either that genotype exists as a whole individual, or it does not exist — it either has a frequency of one per thousand, or zero. There is no 'in-between' when dealing with individuals that are quantized into whole-bodies. This difficulty is handled by Haldane, and by virtually all textbooks today, in the same way — by using non-quantized individuals. To greatly simplify the math, and to generalize the results, they allow a genotype to exist at its expected frequency (without having to quantize the genotype into, say, 1000 whole-bodies). Put simply, Haldane assumed non-quantized individuals, not infinite population size. If evolutionists want to throw-out that simplifying assumption, then they would have to throw-out virtually all of today's evolutionary genetics textbooks. And it still would not solve Haldane's Dilemma.

1,667 substitutions = 10,000,000 / (20 * 300)
Substitutions = (Years) / [(Years / Generation) * (Generations / Substitution)]