The issue with DEILD (and WILD for that matter) is to have a balanced alertness. Enough to trick your body into sleep and mind into REM, while sneakingly staying conscious behind the scenes so to speak.

I have DEILDed three times. Every time it happened in a matter of seconds. I was laying still, and a second later I felt vibrations and then a dream scene formed rather quickly, though I was too excited to jump into the dream. You should be relaxed and just wait for the dream to stabilize properly before you enter. It's like watching TV and then finally decide to enter the TV (very true analogy).

I think it's really important that your room is pitch black so that you do not get any external at all stimuli. This will make it a lot easier in my experience.

Good luck!