We'd like to render a font stack from Typekit and paint a large cover image above the fold of our homepage after document completion. Since asynchronously loading anything generally looks choppy, we fade in the affected elements when it's done. Sure, it gives a much smoother feeling and fast load times, but I have a concern about SEO.
While Typekit loads, h1, h2 and the page's leading paragraph are sent down the wire with an invisible style (but still technically exist as static html). Even though they appear to a user only milliseconds later, I'm concerned that a search engine's initial request is met with a page whose best descriptive assets are marked as invisible.
Both UX and SEO have high value to our business model, so we're asking for some perspective to make the right kind of trade off. Our site has a high domain authority compared to our competition, and sales keyword competition is high. Will this UX improvement damage our On-Page SEO? If so and purely from an SEO perspective, roughly how serious will the impact be?
We're eager to hear any advice or comments on this. Thanks a lot.