First three months fact finding mission

Use the first three months to ask every question you can think of. You're new! Of course you have questions, even if you are familiar with the company. In the beginning, people are more generous with their time. Talk to as many people you can on your informal fact finding mission and take lots of notes, then assess it all together. Talking with people and seeing your notes together will give you a good sense of the landscape, the gaps, and the early wins. You'll feel more grounded with all the info up your sleeve. The book The First 90 Days has been helpful for a lot of people.