So i am attempting to have a lucid dream using the WILD tech, this is something I really want to master as I want to have them more often. But I do not know how long to expect to wait until I enter the dream.
How long does it usually take you from lying down to entering the dream?
That varies on few things and that’s not all of them! 
Well, when you wake up for WBTB you need to know when your next REM cycle is. Then the time that you are awake is also crucial, if you are awake to long you will need more time to fall asleep, if you are awake to short you will fall asleep before entering dream…
So when you get that going you will know how much you need. I would advice waking up naturally, then your chances to getting closer to an REM cycle are greater and about WBTB I can’t tell you how long to stay awake, you need to experiment with that!
Now to answer your question - I don’t know. Because I don’t pay attention on time but if I have to guess I need to say I don’t know and if I’m need to REALLY guess I will say from 10 - 20 minutes, but that is far from correct estimation of time… 