There are dfinitely many directions to take. I'll try to distill down to two metrics across external & internal GTM KPIs:
The X in days depends on the type of business you're in. For B2C you'll focus on MRR and shorter conversion cycles, likely within the first 15-30 days. For B2B align it with your avg sales cycle for prospects and 75% of the time for customer add-ons.
Ideally, it's a combination of the GM, product management and product marketing. The GM would set the overall business goals for the year or quarter including revenue. The PM often drives the product launch adoption and revenue goals for that product. PMM often builds the plan with the metrics to help back into those goals.
The important thing is that if you see a gap, make sure that someone is owning all of these goals, otherwise, it will be meaningless to have launch metrics.
This is challenging indeed and something I've had to deal with at every company I've worked for. What I've fund helps keep me and the business teams sain is to plan to launch features 14 days after the official planned released date. This makes product nervous most of the time, but most of the time they're also delayed so it all works out in the end.
I think you’re asking if it’s behind a pay wall and not just a free product? If that’s the case, you need material (video!) that can act as a demo, people want to see product, not just read about it. Salespeople who can give great demos and free trials are often a really effective a launch tool.
Goes back to the shared goals - which at a high level, are hard to argue with - revenue, cost savings, customer success, etc. Once you get that common agreement, then it's about the strategy / the "how" to get there. If there are disagreements here, I would start with trying to understand why and seeing it from both of their vantage points. Then trying to see if you can get them 1:1 to understand the other point of view or better yet, get them to talk to each other. Ultimately though if all that doesn't work, you may need to get a tie breaker that's someone else and who they will listen to.