Its Okay to Postpone Journaling...for a little bit.
In the middle of the creative process of selecting colors, patterns, embellishments and layout design, it may be difficult to switch gears and write a short statement of the pictures themselves. There is nothing wrong with setting a nearly-complete layout off to the side to add the journaling later (but not too much later) on. This is especially true if you are at a crop or engaged in a movie while you scrap.
DO have a plan for when you will add the journaling. This is a matter of choice: every 5 layouts? Once a week? Once a month? This is entirely up to you. You will probably find once you get in the groove of writing, the task is completed easily and quickly.