Currently discounts created in the Ongoing app apply to all future recurring orders.
The ability to create a discount for only the 1st order is a new feature coming soon.
Here's a workaround.
To create a discount on a subscription for the first order only, you accomplish this with Shopify Discounts.
From Shopify, click Discounts
Click Create Discount
Click Amount Off Products
For Method: Click Discount Code, not automatic
For Purchase Type: Click Subscriptions
For Applies to: You can either choose All subscription products in a specific collection (and then choose the collection) or Specific subscription products and then select the subscription products you want it to apply to only
For the Recurring Payments for Subscriptions, choose "Limit discount to the first payment"
Choose a start and end date to make it active
Review the summary and click Save.
Make sure to run a test order and see how the subscription discount works on your current subscription product, especially if you already have an automatic subscription discount that you created on Ongoing on the subscription plan.
To let your customers know about this discount code, you can email it, place it in the product description, and also add an announcement banner to your website.
Note: Automatic discounts do not work with Shopify Subscriptions. However, Discount codes do work with Shopify subscriptions. Ongoing automatically works with Shopify Discount codes :)
HELPFUL RESOURCES:
✅ For free shipping discount code on first order, that can be achieved through Shopify's discount codes using this tutorial
✅For a free first subscription order (100% off first recurring order) , that can be achieved via Shopify discounts codes by doing 100% discount on the first recurring order only using this tutorial.
✅ For a heavily discount first subscription order, this can be done via Shopify discount codes, using the "Amount of Orders" discount type, where you can create a percentage discount that is only applicable to the first order and then falls off, using this tutorial
Please note Shopify "automatic" discounts only apply to one-time purchases & not subscriptions so you'll want to not use that option when creating a discount code.