Only one way to find out!
Not a question I can answer definitely. The butterfly garden seed packets are usually a mixture of a bunch of different kinds of plants. If so, maybe it is too late for some, but not for others.
Your average last frost date was back 3/20. But that just means you can't plant them before that, doesn't mean you can't plant them after. You should be fine, you have a long season there. The trouble for some of us in colder climes, for some plants, planting too late can mean it won't have time to grow to maturity, flower or fruit or whatever, before the fall frost hits. You won't have that problem since your first frost isn't due until 11/20. For some cool weather crops, planting too late can mean it gets hot too soon for things (eg cabbage and broccoli) that don't like hot. But since it never gets real hot in SF, that's not much of a problem either... go for it!
Just be sure to plant them in a very sunny area. Most all of the butterfly attractor plants like lots of sun. If you are in SF (not some of the surrounding areas) enough sunshine can be hard to come by, foggy a lot.