Sounds interesting. I emailed you. That said I also did a bit of googling and there are some Shopify waitlist apps which might work for you already. As much as I'd like to trade coding for drawers, I'm also a KISS fan and can't see a great reason to reinvent the wheel unless you have special business logic you want to add
Here's a back-in-stock button where users would get an email when the item is available again. It's a waitlist, but it's unordered so anyone who waitlisted gets a chance to buy it when it comes back in stock. $20-40/month:
Back in Stock notifies your customers when you’ve restocked their desired products, sending alerts through push notifications, emails, and texts.
apps.shopify.com
This one is free I think and has a pre-order button. You can charge people at that time or when it becomes available:
Caution This is an advanced tutorial and is not supported by Shopify. Knowledge of HTML, CSS, JavaScript, and Liquid is required. Consider hiring a Shopify Expert if you aren't comfortable doing the steps in the tutorial. If you have products that are out of stock, you can sell them as...
community.shopify.com
This one looks like it allows everyone to join a waitlist, and then you have the option of selecting people and making the item available to them when it comes back in stock (if you want to avoid a "free for all" by 100 people trying to nab 5 drawer kits). $15/month:
Boost your store's sales performance with Wait.li's viral, referral-based waiting lists. Turn customers into enthusiastic promoters and elevate your sales.
apps.shopify.com