I have listed a few tips below to help you gain the best possible engagement during this once in a while event.
Extend Your Reach!
Now you want to gain as much reach as possible within a certain time frame to get people hyped about the grand opening of your online store. To help you gain a much further reach, try reaching out to your local press or even bloggers who deliver content with a similar kind of field to your business. Get bloggers and writers to spread the news about your online store grand opening via their group of followers. Generally speaking, the size of their audience will vary, but if you can target the writers and bloggers with varied amounts of followers as these will suit your company/business better.
One social site that is great for advertising is Reddit. It's free to create an account and your post could get shared with hundreds of different communities. This will in turn, help to create a larger appeal regarding your launch day. Just be careful when posting a subreddit and stick to the rules of posting so that your content does not get banned.
Use Other Social Media Channels
As well as Reddit there are many other social platforms to make use of such as the all mighty Facebook. Instagram and Twitter. The more of an uproar you can bring your business, the better. Post about your business's upcoming online store launch on your personal and business social media accounts.
Ask Friends and Family to Share
I'm sure your friends and family are rooting for you and your company to do well, so why not use them as another free marketing tool. Get your friends and family involved with the promotion and get them to share and spread the news!
In the end, content really is key when trying to build hype around your launch day and it shouldn't be taken lightly. Make sure you are posting regularly out to each one of your social media accounts and ask your friends and family to do the same. This way you can be sure that you will gain at least some form of engagement when launch day comes around.