I did my first Century last month (Camp Pendleton to Huntington Beach and back via PCH), three months after I started road biking. I finished it in 6:41. It was easy but for the last 10 miles when the temps started getting to me.
My training plan was to just ride. 20 to 30 milers twice to three times a week and a long 50 to 70 miler on Saturdays with my Century Buddy.
My day of the ride plan was simple. Drink constantly and eat every 20 miles. I brought bananas, Mooncakes and M&Ms. I had substantial food at the halfway mark and a big sweet pastry at around 70 miles. I also had a pint of milk at the 95 mile mark.
For comfort I had my Brooks saddle, gel filled gloves and a good balance of riding in the drops, hoods and tops. I kept my RPMs at an easy high (85 to 95) and shifted when practical instead of mashing. Felt good after the ride and in fact am ready to try it again this month.