Storrito stickers stay visible for the entire length of the Story card they're added to. There's currently no way to limit a sticker, such as a link, poll, or quiz sticker, to appear during only part of a video or image.
When you place a sticker in Storrito's editor, it's attached to the whole Story card, not to a specific moment within it. There's no in/out timer for stickers, so once a sticker is added, it shows from the first frame to the last.
If you only want a sticker to feel relevant to part of a longer video, split the video into separate Story cards and add the sticker only to the card it applies to. Each card in a Story can carry its own set of stickers.
If you want to interact with your audience through stickers like polls and questions, Storrito handles the creating and scheduling; checking responses still happens in the Instagram app.