If you want to use visualising to set your intention, then using a visualisation which helps you remember what you intend to do, is best. So maybe visualise a dream you had recently, best if it’s a common dream-sign for you, but see yourself get lucid when you see it.
It doesn’t have to be done in conjunction with WBTB but it helps.
You don’t have to visualise, you can also use a mantra and skip visualisation if it causes problems. A good guide to developing you mantra is here.