You can worry about all types of training regiments especailly if your goal is to complete a century but I always tell everyone first thing you need to do is just RIDE. Get on the bike and go somewhere. Spend as much time on the saddle as possible. Going slow, going fast doesn't matter. You just need to ride. The key is to build a good "base" of mileage. It would be nice to see you consistantly doing 100 - 150, maybe 200 miles a week before you attempt a century.

BTW doing a century is not all that big a deal. OK it is if you want to finish in a fast time (less than 7 hours) , be very fresh afterwards, and next day not be sore. Otherwise, most anyone that rides can do a century. You just might not feel so good after (or during). As you get back into riding, pay attention to what stuff your body craves and does well on. Learning to avoid bonking is a big plus in doing a century.

So just ride and just learn to eat the right stuff for you (nutrition is a very personal thing). Not so hard, not all that much to remember. By summer you will be century ready.