From the time I've been following, releases have been late, so there's no point in counting on a release until it shows up. Even typing that, I can already hear, "Yeah, I get it. But ball park..."
According to this site https://calomel.org/zfs_health_check_script.htmlZFSd fault management daemon doesn't arrive until FreeBSD10. Until then, you can have a zfs health check script, which in on that page.