Hank here from Shopify!
Depending on what way you want to set up the discount for pre-orders, there may be multiple ways you can think of doing this.
One way you can do this is to create a manual discount within your admin and assign it to a certain group of customers. Another way to look at this is through the likes of an app like Locksmith, that way you can create a certain landing page, or page within your website, that certain customers would be allowed view.
If you do not already have an app for pre-orders, I will share this list with you for apps within our app store. Another way you can allow pre-orders on your product page is through the likes of advanced coding, which I have a tutorial for you here.
Similar to the pre-order query, allowing your customers to select a delivery date is another option that can be done via the likes of an app. It is a very good measure for your store, as it empowers the customer and allows for a much more suitable ordering experience. I have some apps here for you to take a look at to see which option would best suit your store.
Then another option I have for you is if you wish to reach out to the likes of one of our Shopify Experts, who you can hire to do almost any custom work on your store.
If you were to reach out to them about this query, they would be able to resolve this issue for you.
Let me know how you find this, or if you have any further questions for me!
All the best,