For a lot of men the adjustment is impaired by their suppressing or denying feelings. If this is not resolved, it will in time erode the husband-wife relationship. Don't be afraid of your feelings, or of not knowing all the answers. Talk to each other. Don't be afraid of asking for professional assistance.
Marriage therapy is usually short term and non-judgmental.
Run interference for your spouse and baby. People you have not heard from in years will tramp into your life. Politely organize visitation so that it is convenient for your wife and baby. If you are not a master chef, and your spouse has not stocked up the refrigerator, go to the store and get some frozen dinners. They are cheaper and better nutritionally balanced than fast food.