I recently found that when i am dd, i always say 'pretend'. for example i will say pretend there is a house here, or pretend i am at such and such place. i will often say this to myself or out load when imaganing objects or scenery around me. and only when i am deeply into my dd that i dont notice my surrondings. I only noticed how much i do this when i noticed 2, 6 year old girls playing tea sets they were saying pretend your the doctor pretend i am the wife ect, I suppose in a way dd is like pretending and playing make belief like a child but in a more refined and grown up way.
I did that when I first started dd but now find it unnecessary. I don't know if that's because I'm just so much more immersed or because I started using music more to help with the transition and therefore needed the phrase less to transition me to my dd world.