Sounds like you are doing great already. The more you ride, the better you'll get. Floyd Landis says, "If you wanna get better at hills, ride hills." He's pretty simplistic when it comes to this kind of stuff. Dh is always telling me how riding hills also helps you with the flats. The more hills you do, the easier the flats start to feel and the faster you do them.

I'm no expert, but I'd say April is a very do-able goal for your first century. Especially if your main goal is to simply finish it without worrying too much about speed.

I'm doing my first century next weekend. Dh got us a tandem a year ago, which we rode some in the fall, but not at all in the winter. Then started back up in the Spring. Then I got my own single in June and got way more excited about riding. We're doing the century on the tandem. I think it's a great way for me to do my first one. (Dh is an experienced and very strong cyclist, so yay for me.) I plan on doing something shorter for my first organized ride on my single. Like 50 or something. I'm sure after the century, 50 on my single will seem like a piece of cake, which is what I'm hoping! Eventually I'll shoot for a century on my single, for sure by next season.

Sounds like you've gotten lots of good advice. I think I'll check out that book someone recommended. Good luck training for your first century! I'm sure you'll do well.