Act as a seasoned Instagram marketing specialist with 5+ years of experience in social media strategy. Create a step-by-step guide on how to effectively use Instagram’s countdown sticker to [PROMOTE AN EVENT, LAUNCH, OR SPECIAL OFFER]. Include best practices for [ENGAGING YOUR AUDIENCE] and tips on [OPTIMIZING THE COUNTDOWN FOR MAXIMUM IMPACT]. Explain how to customize the sticker’s design, set the timer, and track engagement metrics. Provide examples of creative captions and call-to-actions to pair with the sticker. Tailor the advice for [BUSINESSES, INFLUENCERS, OR PERSONAL USERS] based on their goals.