Swim Lessons

I'm turning to you guys for help here!  Hudson LOVES the pool.  In his kiddie pool he sticks his face under the water and comes up laughing (although he doesn't get the hold-your-breath concept and often gets a mouth full of water).  In our big neighborhood pool he loves sticking his head under the mushroom water fountain thingy, running around in the 1 foot deep section, and wants to be carried out to the part where he can't touch.  In fact, he wants me to let go of him and doesn't get that he will go under and can't swim in this part!  He will take off walking right toward the pool and I don't doubt that he would just walk right into it without a second thought if we weren't watching him.  His fearlessness scares me to death!

So that brings me to my question:  At what age is the best to start swimming lessons?  I did consider the Infant Swim Rescue classes but I was worried that it would make him afraid of the water and my nerves couldn't take it (I cry watching this video and I don't even know the baby!).  I'm considering doing regular lessons at Swim Atlanta but I'm worried that he will forget what he would learn.  Is this something we should do every "semester" they offer classes?  Should I start early or just tough out these trying times?