For me it seems as if it only takes a matter of a few minutes, but there is a time that is kind of "void" for me, where I go from nothing. Then it may be 10 seconds or 5 minutes (who knows) before I wake up in a dream. Let your body fall asleep and train yourself to do a reality check everytime after you wake up.

Also the vibrations you feel might be your body testing you to see if it is truly asleep.

Your body is clever when it comes to this and will tell you that it is uncomfortable simply to see if you move, and if you move it tells your mind and body that you are not ready to go into sleep mode.

Let yourself fall asleep, and don't dwell too hard on your thoughts, trying too hard might be where your downfall lies.

Sometimes we only find things after we stop looking for them right?