It probably shouldn't take you too long to get a lucid where you don't wake up immediately. Just remember to stay calm as you realize you're dreaming, and remember to have patience. assuming you're not about to die for whatever reason, you should have plenty of nights ahead of you to practice. Don't give up even if it takes longer than you expected, because everyone succeeds eventually.

Also try doing the usual things to prolong your dreams, like spinning or rubbing your hands together. If you can remember to do this as soon as you gain lucidity, you'll have a much better chance of staying lucid. Just start rubbing your hands together furiously the next time you turn lucid and concentrate on the sensation of movement. It works for me. ^.^