Too often I see photographers release a handful of blogs 6 months to a year after they shot the wedding. While that's better than nothing, they're missing out on the initial surge of traffic when a client shares the blog on their social media feeds, because it's the first place they can see their photos.
Your best bet for sharing your shoots is when your client is not only willing, but WANTING to share your link. We put up blogs before we deliver most of the time, because when people see their photos, they will share them with all of their friends and family on their social media channels, if you wait too long, you miss out on that giant splash of traffic.
While you still get most of the benefit with SEO even by posting late, you miss out on a lot of the benefits.