Keep in mind when planting that Winky Purple and White is thought of as hardy, so it can be safe to leave outdoors for the majority of winter (although if in doubt, using a row cover is often a good idea).
Soil temperature should be kept higher than
18°C / 64°F to ensure good germination.
By our calculations, you should look at sowing Winky Purple and White about 56 days before your last frost date.
As Winky Purple and White is hardy, ensure temperatures are mild enough to plant out - wait until after your last frost date to be on the safe side.