Do you launch your SaaS before the PH launch?

Yes - definitely. A closed beta launch to gather feedback gives you valuable insights and feedback from your users and allows you to polish your product before launching to the public.

I will recommend making a first PH launch as soon as you can. Product hunt allows relaunching after 6 months if you release new features. Even a launch finishing in the top 20 can help you get initial traction to collect feedback about your saas. If you are interested in information about how to prepare a no-frill first launch, you can check out the action template that I'm hunting today.

I think it's a great way to generate support for the actual launch, so I see no reason not to do it. However, I would be careful, since you can only extend or shorten the launch date by a couple of days once you set it, so if there's any large delays that come up, or if you finish much earlier than expected, it could cause some issues. As a best practice, I would pre-launch a week in advance, and make sure development is finished a few days before launch rather than the day of launch to iron out any major bugs.

Definitely launch an MVP before

Yes, I would do it for sure, as you want to test it with a probably smaller open group first to refine the flow before going full in.

We did a pre-launch before the launch on PH. That worked as it generated a positive word of mouth and also validated the product.