No, you don't need to worry about any builds going in. The first time you play though the campaign will be fun and easy regardless. Once you hit 70, you start looking into builds. Right now all classes have strong endgame, just some are stronger (DH) and some don't require thought or strategy (barb). And even if you want to change your class, leveling alts is much faster than the first time leveling. Going into it, I wouldn't worry about anything. Just enjoy the trip. You wouldn't know what people are talking about anyways until you have access to the majority of your skills/ruins.