Keep in mind when planting that Isabella 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).
Growing Isabella from seed
By our calculations, you should look at sowing Isabella about 90 days before your last frost date.
Transplanting Isabella
Ensure that temperatures are mild and all chance of frost has passed before planting out, as Isabella is a hardy plant.