By far the most helpful guide for what to plant, and when is this West Coast Seed Planting chart. Our region is South Coastal BC.
The guides (vegetables, herbs, and flowers) will tell you when to start things indoors, and when to transplant. Or, when you can direct sow things into the ground. And then also when to cover things up to give them a bit of protection from frost.
Remember that you don’t have to plant things all at once. For example, you can direct sow lettuce from May until September. Do it every couple of weeks for a continual harvest for many months of the year!
Another example is spinach, which doesn’t love the hottest days of summer. Plant it early for a harvest in June, and then again in August for a harvest in the fall.