I was able to get a working prototype of Brisa Videos in about a week - a really bad UI to add elements, clicking to create animations and change styles by typing in CSS values.
Then integrated it with AnimeJS so animations could be played back. Last, used the SVG-to-Canvas method to create images of each frame.
After I got that working, I spent a couple months building a backend and converting to a backend renderer. Implemented a Stripe payment system for the first time for my own app, and enabled signups!