Just to agree that pups do need to be about a year old before they do much agility work at all to make sure that they are fully developed. Lots of work too early can cause joint problems and injuries.
Having said that, there are things that you can do to prepare your pup that will come in handy when you do start agility.
1/ A good wait. Your dog will be faster than you so if you can get a head start by leaving him/her in a wait at the start this will be handy and also really helps as the courses get more difficult as you go up through the grades. Make sure you are consistent with your release command - I use "OK" but "go" is probably a good one - nice and short.
2/ Teach left and right. It is useful if you can holler directional commands to your pooch to steer him/her the right way as they are whizzing around the course in front of you. These can be taught by repitition whilst out on a walk. If you go to turn just say the directional command first and they will soon pick it up.
3/ Get your pup used to walking on both sides of you. When you run at agility the dog will need to sometimes be on your left and sometimes your right. If you do a lot of obedience work where a dog is always on your left this can cause a problem when starting agility - ask your obedience instructor if they mind if work your dog on both sides and hopefully they will be flexible if you explain the reason for your request.
Good luck but please don't be tempted to do too much too soon and start yourself doing equipment at home. You could develop bad habits which will be difficult to break when you do start to go to a club. Once a dog has learnt to do something the wrong way it is really difficult to change it so the first few leassons are very important.