Welcome to TE! Congratulations on your first organized ride. You are making steps in the right direction for your health. As for when to increase duration or intensity, others who have biked longer may have better advice. For me, I just increase both as my body feels ready for it.
Keep coming here. This forum is awesome and will keep you motivated. Again, welcome.
Jennifer
“Live as if you were to die tomorrow. Learn as if you were to live forever.”
-Mahatma Gandhi
"We are what we repeatedly do. Excellence, therefore, is not an act but a habit."
-Aristotle