Dreams can happen at anytime during sleep. I don't know when you go to bed, so I can't say for sure if most of them happen after 4:40.

The best technique to use is a personal thing. Myself, I am best at the techniques that fall under the DILD category - that is, where I become lucid when I'm already in the dream. This encompasses techniques like DILD itself, MILD, EILD, and others. You may be a better WILD'er. How long they take depends on you. If you can succeed by waiting 10 minutes then returning to bed then good, but if you need an hour then hey, whatever works for you. You'll have to experiment and figure it out.