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