Well, a lot of seeds germinate irregular, like Delphiniums. It depends on how many you want to grow.
Every year I sow more than 400 species, some of them germinate, some not.
If I have germination I'll see how many I want of that plant. If there are just a few and I want a lot, I'll wait at least a week. I'll wait longer if the already germinated ones are still healthy and not leggy. If they get leggy or getting less healthy, I transplant them and will forget about the others, I'll have at least some.