Copied over from a similar question:
There are a lot of things you could do - and it's easy to get distracted as a product marketer.
First 30 days - Listen, listen, listen. Ask a TON of questions. Hold back from providing ideas unless you are really sure about it. Help others behind the scenes on ongoing projects with work you are good at - like writing or editing copy, preparing slides, etc. Help them look good and make allies. This is also a great way to learn the business. Talk to customers - jump in on existing calls and ask good questions. Get familiar with basic analytics and KPIs - need to know what needle to move and what drives it.
30-60 days - Make a success plan & set concrete expectations. Create a list of things you are going to focus on to make the most impact on the business. Separate quick wins from strategic work. Have a healthy debate with your boss and cross-functional leaders in sales, product, and customer success. Focus on your first big win that can be accomplished in under 30 days. Get an A in that even if you let everything else fail or push to the next 30 days. Figure out which fires you are going to let burn. Also, do most of your work in the open - it's often not a good idea to wait for the "big reveal". Surprises are not your friends. We tend to miss out on helpful feedback others can provide when we are missing context - this is critical during the early days.
60-90 days - Create momentum. Ask leadership for informal feedback - how you are doing and where you can tweak things. Once aligned, I would focus on the next big win while delivering smaller, tangible outcomes that line up with your success plan. The most important thing a product marketer should be doing through this journey is saying "no" enough. Smaller companies tend to see everything that is not about generating leads to be product marketing's job. While you could make that argument, it is important to say no to those seemingly urgent things and let those fires burn. Jumping on things because the CEO/CMO said so without considering the tradeoffs to your current priorities can be your biggest enemy.