First Ultrasound

My first ultrasound is tomorrow I'm almost 12 weeks, I haven't heard heartbeat or anything so I'm excited. Someone told me to drink orange juice another said some caffeine? Are these old wives tales? I haven't had any caffeine my entire pregnancy (so far) and don't think I'll try that one. Just wondering what to expect. Sorry for the babbling I'm just excited and nervous and super ready to see this little baby!