It's a question of stability. Oak and pine react to changes in atmospheric moisture at different rates, which means that overcladding one with the other is potentislly risky. I'm not a fsn of laminate over pine stairs, and for the same reason, but at least with laminate is used it'll br cheaper to rip out! (Sorry, but Iworked on a new build a few years ago where they did just that on morecthan 20 top floor duplexes - about half of them have required remedial wkrk to correct creaking)
Try more like a month, or longer, in the wetter months of the year like now. Solid timber is likely to come in with a MC (moisture content) of 12 to 14% if air dried and stored indoors - timbers in a centrally heated house will stabilise at around 8 to 10%
That implies you are cutting the nosing back to get a square edge, but cutting the nosing flush to tbe riser weakens the stairs - the underside of the treads are grooved to hold the top edges of the risers, which are additionly stiffened using rub glued glue blocks. This aline makes flush cutting inadvisable. It may not make any difference in the short term, but over time, and particularly when the stairs are subjected to heavy loading, the tops of the stringers can work.loose and the glue blocks fall off