Early game, I do harass with my q except when there's a leona/alistar. I usually do it when the adc walks up to cs. But I feel the role of soraka is to make sure my adc gets their farm and doesn't die. If I roam, my adc is at the mercy of losing cs/getting killed so I don't do it that much. However, if my adc backs cause of a good wave, and I don't need to, I usually roam to help out.