Prunus x yedoensis (Yoshino Cherry):
2 - 3 months cold stratification (moist chill) and is best sown as soon after ripening, not stored dry too long. The seed can be slow, sometimes taking multiple cycles of fluctuating temperatures, up to 18 months to germinate.

You don't say where you live, but you could sow and place the pots outdoors now if you are about at a Z8 or colder. Or use your refrigerator for the moist chill if you don't think you can expose them to several weeks of temps of approx. 40F or lower outdoors.