Keep in mind when planting that Chequerboard 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.
Soil temperature should be kept higher than
68°C / 154°F to ensure good germination.
By our calculations, you should look at sowing Chequerboard about 77 days before your last frost date.
Ensure that temperatures are mild and all chance of frost has passed before planting out, as Chequerboard is a tender plant.