Keep in mind when planting that cinderella is thought of as very hardy, so this plant will tend to survive through freezing conditions. cinderella requires a loamy soil with a ph of 6.0 - 7.0 - it grows best in weakly acidic soil to neutral soil.
By our calculations, you should look at sowing cinderella about 56 days before your last frost date.
Ensure that temperatures are mild and all chance of frost has passed before planting out, as cinderella is a very hardy plant.