I am joining a new team that has big project with a strict deadline

Danielle,

I'm curious why being a program manager would enable you to run a big project. Projects and programs are different things and require different capabilities. Be clear about the terms you use and the responsibility assigned to you by the role. Maybe your company also does not have this clarity,

In a project, the core team is key, having 1:1s which each and team building would be one of my first steps.

A working relationship with the sponsor is important, formally at least monthly, informally on a weekly base.

Get a mentor from outside your project.

This is a simple question with a very complex answer that could be out of line due to a lack of information.

If you were hired as a Program Manager, and are being asked to mange a project, which is a job for a Project Manager not a Program Manager, I would dig into that a little more deeply. Does your organization know the difference between the two roles? Were you hired to manage an important program, and this fhe first of the projects in the program that someone deemed had to go first? Are there other projects? How are they related? A program is a series of related projects, all of which must be executed (not necessarily at the same time) to achieve the expected business benefits.

Maybe you were hired to set up a PMO, to manage the execution of the all the projects in the program, with more on the way, a major task very different from managing a project. If this is a case, dig into the PMO Value Ring Methodology from PMOGA, recently acquired by PMI. This is a fabulous methodology that will get anyone starting a PMO off on the right foot, first achieving executive alignment based on expected benefits with PMO functions to achieve those benefits following, staffing plans that follow the functions, and so much more.

So, you have some work to do to find out why you are really there, and the expectations of those who hired you.

If you do find out that you are expected to manage a project, then the standard tasks apply, some of which has been mentioned by my colleagues Thomas and Kiron already. Look for documents that would be input to the project charter like the business case, organizational strategy, etc. so you understand clearly why the project was authorized, get the charter done involving all appropriate stakeholders and get it approved formally first to ensure everyone is on the same page.

Then figure out how you will run the project. If predictive, plan the project, focusing on the WBS, the required deliverables and how you will manage the project considering the usual ten knowledge areas. The organization will be looking for a schedule, proposed budget, resource requirements, risks, and so on.

If Agile, start with getting a product owner to help with the product backlog, procuring a team, sizing the backlog, and so on.

Sorry - you asked what might be your first steps in the first 30 days, and I fear I went on a little too long.