Software Development Life-cycle - MVP in 3 months! What's the correct approach?

I just joined a company with one developer who manages his code using GIT. There is also an AWS instance where the developer run tests and nothing else in terms of infrastructure. The company is growing fast and more developers will be joining the team soon and the CEO wants to ship some MVP ASAP. (around 3 months)

• Where would you begin? What needs to be done and in what order....

I was thinking first move the testing to CircleCI, then setup test, staging, production environments... but would you do next ?