Keep in mind when planting that Century Fire is thought of as tender, so it is really important to ensure that the outside temperature is well above freezing before planting or moving outdoors. Ensure your soil has a ph of between 6.1 and 7.5 as Century Fire is a weakly acidic soil - weakly alkaline soil loving plant.
By our calculations, you should look at sowing Century Fire about 49 days before your last frost date.
Ensure that temperatures are mild and all chance of frost has passed before planting out, as Century Fire is a tender plant.