Depends if you're talking private lessons or group lessons. Private lessons are never a waste of time. The instructor will determine your level and work from there. Group lessons, meh. They have beginner, intermediate, advanced, and you won't necessarily fit into any of them.
If you have the bucks, get a group lesson on the first day to get the basics (you benefit a lot from watching what the other students are doing wrong) and a private lesson on the second day.