With a decent amount of training, you could be ready in June, and September should be pretty easy to do.

For what you want to do and where you are fitness-wise, distance is more important than speed. Over time, you will want to slowly work up to rides that are 2-3 hours of length. If you can do that 2-3 times a length, that will get you most of the way there.

You will also need some longer rides (say, 4-5 hours) and learn what to eat/drink while you ride.

I also recommend some good shorts (very important on longer rides), and you may also consider clipless pedals and shoes if you think you're going to keep doing this. A saddle that works well for you (you may have to try several), and a bike fit are also great, but probably not required for the ride.

If it's especially hilly (and it probably is *to you* if you are just getting into riding), we can give you some tips on that, but I wouldn't worry about that until May or so.