I was 35 last year when I bought my first road bike. If you have mountain bike and bmx experience, then you have a more solid cycling background than I do. You know you can start off in a more upright position on a drop bar bike by adjusting headset spacers and the stem, right? Other than that, relax and get some miles in. First month (Feb 2018) I did about 20-30 miles a week, the next month I started bike commuting more confidently and did 50. By April, 100+ miles a week was my norm.